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Published studies on hypochlorous acid, each with the concentration, pH, contact time and result, and a link to the original. Filter by organism, setting, concentration, evidence type and finding.

Concentration bands: <50, 50–200, >200 ppm available chlorine.
Supports activity

E. coli O157:H7, Salmonella and Listeria in electrolyzed oxidizing water

Venkitanarayanan KS, Ezeike GO, Hung YC, Doyle MP. Efficacy of electrolyzed oxidizing water for inactivating Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes. Appl Environ Microbiol. 1999;65(9):4276-4279.

Concentration
Not stated in abstract
pH
Acidic EO water
Contact time
5–10 min (4–23 °C)
Surface / soil
Suspension, ~10⁸ CFU/mL

Result: About 7-log reduction of all three pathogens in 5 min; complete inactivation by 10 min. Authors note applications need validation.

BacteriaFoodLab / in vitro
Venkitanarayanan 1999
DOI →
PubMed 10473453
Supports activity

How pH and amperage shape EO water’s kill of B. cereus

Len SV, Hung YC, Erickson M, Kim C. Ultraviolet spectrophotometric characterization and bactericidal properties of electrolyzed oxidizing water as influenced by amperage and pH. J Food Prot. 2000;63(11):1534-1537.

Concentration
Varied
pH
pH range tested
Contact time
Not stated
Surface / soil
Suspension

Result: HOCl concentration and kill both peaked near pH 4; HOCl correlated with kill (r = 0.95), pointing to HOCl rather than OCl⁻ as the main agent.

BacteriaFoodLab / in vitro
Len 2000
DOI →
PubMed 11079696
Supports activity

Neutral EO water vs. other chlorine sanitizers with organic load

Ogunniyi AD, Dandie CE, Ferro S, et al. Comparative antibacterial activities of neutral electrolyzed oxidizing water and other chlorine-based sanitizers. Sci Rep. 2019;9:19955.

Concentration
<1 to 20 mg/L free chlorine
pH
6–9.2
Contact time
Under 2 min (clean water)
Surface / soil
Clean water and high dissolved organic carbon

Result: 4–6 log in under 2 min in clean water; at 20 mg/L with high organic load, EOW outperformed NaOCl and ClO₂. One author declared an EOW-industry affiliation.

BacteriaFoodLab / in vitro
Ogunniyi 2019
DOI →
PubMed 31882630
Supports activity

Slightly acidic EW vs. pathogens across water hardness

Kim HJ, Tango CN, Chelliah R, Oh DH. Sanitization efficacy of slightly acidic electrolyzed water against pure cultures of E. coli, Salmonella Typhimurium, S. aureus and B. cereus spores, in comparison with different water hardness. Sci Rep. 2019;9:4348.

Concentration
20 ppm
pH
Slightly acidic
Contact time
1 min
Surface / soil
Pure cultures

Result: Vegetative pathogens fully inactivated within 1 min; feedwater source and hardness affected SAEW production.

BacteriaBacterial sporesFoodLab / in vitro
Kim 2019
DOI →
PubMed 30867518
Supports activity

Human norovirus on tile and stainless steel, liquid and fog

Park GW, Boston DM, Kase JA, Sampson MN, Sobsey MD. Evaluation of liquid- and fog-based application of Sterilox hypochlorous acid solution for surface inactivation of human norovirus. Appl Environ Microbiol. 2007;73(14):4463-4468.

Concentration
20–200 ppm
pH
Not stated
Contact time
10 min
Surface / soil
Tile, stainless steel; confined-space fog

Result: At least 3-log (99.9%) reduction of human norovirus (RT-PCR), murine norovirus and MS2, as liquid and as fog.

Non-enveloped virusesHealthcareHospitalityLab / in vitro
Park 2007
DOI →
PubMed 17483283
Supports activity

SARS-CoV-2 in suspension and carrier tests

Hatanaka N, Yasugi M, Sato T, Mukamoto M, Yamasaki S. Hypochlorous acid solution is a potent antiviral agent against SARS-CoV-2. J Appl Microbiol. 2022;132(2):1496-1502.

Concentration
28–250 ppm
pH
Not stated
Contact time
10 s (suspension) to 10 min (carrier)
Surface / soil
Suspension with 0.1% FBS; carriers

Result: 28.1 ppm gave 4 log in 10 s; 59.4 ppm went below detection in 10 s. Carrier: 125 ppm/10 min or 250 ppm/5 min gave ≥4 log. Industry-funded.

Enveloped virusesGeneral / labLab / in vitro
Hatanaka 2022
DOI →
PubMed 34480823
Mixed / conditions matter

Influenza and coronavirus with tests simulating practical use

Miyaoka Y, Kabir MH, Hasan MA, et al. Virucidal activity of slightly acidic hypochlorous acid water toward influenza virus and coronavirus with tests simulating practical usage. Virus Res. 2021;297:198383.

Concentration
62–540 ppm
pH
5.2–5.8
Contact time
30 s to 20 min
Surface / soil
Organic matter; rayon wipes; spraying

Result: 62 ppm cut avian influenza and IBV by >3 log in 30 s in suspension, but IBV on carriers resisted and 220 ppm failed on rayon wipes; spraying 300 ppm for 10 min reached undetectable levels.

Enveloped virusesGeneral / labLab / in vitro
Miyaoka 2021
DOI →
PubMed 33705798
Supports activity

Differently manufactured HOCl waters at various pH vs. SARS-CoV-2

Takeda Y, Matsuda S, Jamsransuren D, Ogawa H. Comparison of the SARS-CoV-2-inactivating activities of the differently manufactured hypochlorous acid water products with various pH. J Water Health. 2021;19(3):448-456.

Concentration
Several products
pH
Various
Contact time
Not stated
Surface / soil
Suspension

Result: All products worked when volume and residual chlorine were sufficient; pH 5.0–6.4 products kept chlorine and activity for 21 days; at pH ≤ 3.0 chlorine dropped quickly.

Enveloped virusesGeneral / labLab / in vitro
Takeda 2021
DOI →
PubMed 34152297
Mixed / conditions matter

Dry-fog HOCl and H₂O₂ vs. SARS-CoV-2 and influenza A

Urushidani M, Kawayoshi A, Kotaki T, et al. Inactivation of SARS-CoV-2 and influenza A virus by dry fogging hypochlorous acid solution and hydrogen peroxide solution. PLoS One. 2022;17(4):e0261802.

Concentration
CT-dependent
pH
Not stated
Contact time
CT-dependent
Surface / soil
Unoccupied test chamber

Result: Both fogs inactivated both viruses depending on concentration × time; SARS-CoV-2 needed more. Not evidence for fogging occupied rooms.

Enveloped virusesGeneral / labLab / in vitro
Urushidani 2022
DOI →
PubMed 35389997
Shows limits

SARS-CoV-2 surrogate on steel and vinyl with soil

Hamilton AN, Chandran S, Baker CA, Gibson KE. Surface inactivation of a SARS-CoV-2 surrogate with hypochlorous acid is impacted by surface type, contact time, inoculum matrix, and concentration. Food Environ Virol. 2023;15(2):116-122.

Concentration
500–1000 ppm (sprayed)
pH
Not stated
Contact time
5–60 s
Surface / soil
Steel, vinyl; dried saliva or tripartite soil

Result: Best result only 3.31 log (1000 ppm, steel, 60 s). Authors caution a short spray may not adequately reduce enveloped viruses.

Enveloped virusesFoodLab / in vitro
Hamilton 2023
DOI →
PubMed 36680664
Supports activity

Government evaluation of HOCl water on objects vs. SARS-CoV-2

NITE (National Institute of Technology and Evaluation, Japan). Final report on the efficacy of alternative disinfection methods against SARS-CoV-2. June 26, 2020.

Concentration
≥35 ppm available chlorine
pH
Not stated
Contact time
Not stated
Surface / soil
Objects

Result: Judged effective on objects, provided soil is removed first and a sufficient volume is used. Government lab report (Japanese), not peer-reviewed.

Enveloped virusesGeneral / labGuideline / gov report
NITE 2020
Source →
Supports activity

Molds and Candida yeasts in vitro

Odorcic S, Haas W, Gilmore MS, Dohlman CH. Fungal infections after Boston type 1 keratoprosthesis implantation: literature review and in vitro antifungal activity of hypochlorous acid. Cornea. 2015;34(12):1599-1605.

Concentration
0.01% (~100 ppm)
pH
Not stated
Contact time
60 s
Surface / soil
In vitro

Result: At least 4-log kill within 60 s of Aspergillus, Fusarium, Mucor, Acremonium and Candida species. In vitro only; ocular clinical context.

Fungi & yeastsHealthcareLab / in vitro
Odorcic 2015
DOI →
PubMed 26488624
Supports activity

Penicillium expansum mold spores with surfactant-modified sanitizers

Okull DO, Demirci A, Rosenberger D, LaBorde LF. Susceptibility of Penicillium expansum spores to sodium hypochlorite, electrolyzed oxidizing water, and chlorine dioxide solutions modified with nonionic surfactants. J Food Prot. 2006;69(8):1944-1948.

Concentration
Varied
pH
Varied
Contact time
Not stated
Surface / soil
Suspension; 4 °C vs 24 °C

Result: Up to 5-log reduction of mold spores; all sanitizers worked less well at 4 °C than at 24 °C.

Fungi & yeastsAgricultureFoodLab / in vitro
Okull 2006
DOI →
PubMed 16924921
Shows limits

Highly purified HOCl water across bacteria, fungi and viruses

Mokudai T, Iwasawa A, Kikuchi K, Niwano Y. Bactericidal, fungicidal, and antiviral activity of highly purified hypochlorous acid water. J Microorg Control. 2026;31(2):67-72.

Concentration
Not stated in abstract
pH
Not stated
Contact time
10 s and longer
Surface / soil
In vitro

Result: Vegetative bacteria, dermatophytes and C. albicans inactivated in 10 s; A. niger needed longer; limited activity against some mycobacteria, spore-formers and enteroviruses.

BacteriaFungi & yeastsBacterial sporesNon-enveloped virusesGeneral / labLab / in vitro
Mokudai 2026
DOI →
PubMed 42270376
Shows limits

Very low-concentration HOCl at neutral and alkaline pH

Kim HJ, Lee JG, Kang JW, et al. Effects of a low concentration hypochlorous acid nasal irrigation solution on bacteria, fungi, and virus. Laryngoscope. 2008;118(10):1862-1867.

Concentration
3.5 ppm
pH
7.0 and 8.4
Contact time
Not stated
Surface / soil
Tap-water solution

Result: More than 99% kill for most bacteria and fungi, except C. albicans; shows how low concentration and high pH reduce activity. Medical context; chemistry evidence only.

BacteriaFungi & yeastsHealthcareLab / in vitro
Kim 2008
DOI →
PubMed 18677274
Supports activity

B. subtilis and B. cereus spores in suspension and on carriers

Zhang C, Li B, Jadeja R, Hung YC. Effects of electrolyzed oxidizing water on inactivation of Bacillus subtilis and Bacillus cereus spores in suspension and on carriers. J Food Sci. 2016;81(1):M144-M149.

Concentration
40–120 mg/L ACC
pH
Acidic and slightly acidic
Contact time
1–6 min
Surface / soil
Suspension; carriers; 0.3% organic soil

Result: 120 mg/L: B. cereus spores undetectable in 2 min; 60 mg/L for 6 min reached non-detectable; 0.3% organic soil reduced the effect.

Bacterial sporesFoodLab / in vitro
Zhang 2016
DOI →
PubMed 26642381
Supports activity

How lowering pH boosts hypochlorite’s sporicidal power

Sil TB, Malyshev D, Aspholm M, Andersson M. Boosting hypochlorite's disinfection power through pH modulation. BMC Microbiol. 2025;25:101.

Concentration
5,000 ppm hypochlorite
pH
7–12
Contact time
10 min
Surface / soil
B. cereus spores

Result: Less than 1 log above pH 11, but a 4-log gain between pH 11 and 9.5 as HOCl forms; shelf life falls steeply below pH 8.5.

Bacterial sporesGeneral / labLab / in vitro
Sil 2025
DOI →
PubMed 40021972
Mixed / conditions matter

Acidified hypochlorite vs. Bacillus and Clostridium spores

Oie S, Obayashi A, Yamasaki H, et al. Disinfection methods for spores of Bacillus atrophaeus, B. anthracis, Clostridium tetani, C. botulinum and C. difficile. Biol Pharm Bull. 2011;34(8):1325-1329.

Concentration
0.5% (5,000 ppm)
pH
Acidified with vinegar vs. plain
Contact time
15 s to 6 h
Surface / soil
Vinyl, plywood

Result: Acidifying (shifting toward HOCl) killed spores on vinyl and plywood within 15 s where plain hypochlorite failed after 1 h; porous plywood resisted up to 6 h. Bleach-strength; not a home recipe.

Bacterial sporesHealthcareLab / in vitro
Oie 2011
DOI →
PubMed 21804226
Shows limits

Stability and sporicidal efficacy of oxidizers vs. C. difficile spores

Brown L, Marshall A, Conway L, et al. Assessing the stability and sporicidal efficacy of oxidizing disinfectants. J Hosp Infect. 2024;149:22-25.

Concentration
1000 ppm chlorine products
pH
Not stated
Contact time
EN 17126 test
Surface / soil
Clean vs. dirty (medical soil)

Result: Chlorine-releasing agents, HOCl included, lost stability and efficacy under dirty conditions; peracetic acid held up.

Bacterial sporesHealthcareLab / in vitro
Brown 2024
DOI →
PubMed 38705474
Supports activity

CDC healthcare guideline: chlorine and chlorine compounds

Rutala WA, Weber DJ, Healthcare Infection Control Practices Advisory Committee (HICPAC). Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008 (last update June 2024). CDC.

Concentration
100 ppm; 5,000 ppm (bleach, C. difficile)
pH
Not stated
Contact time
≤5–10 min
Surface / soil
Guideline summary

Result: Chlorine’s microbicidal activity “is attributed largely to undissociated hypochlorous acid (HOCl)”; disadvantages include “corrosiveness to metals in high concentrations (>500 ppm)” and “inactivation by organic matter.” 100 ppm kills ≥99.9% of B. atrophaeus spores within 5 minutes; 5,000 ppm bleach inactivates 10⁶ C. difficile spores in ≤10 minutes.

Bacterial sporesBacteriaHealthcareGuideline / gov report
CDC 2008
Source →
Supports activity

Stabilized HOCl and biofilm (in vitro)

Sakarya S, Gunay N, Karakulak M, Ozturk B, Ertugrul B. Hypochlorous acid: an ideal wound care agent with powerful microbicidal, antibiofilm, and wound healing potency. Wounds. 2014;26(12):342-350.

Concentration
Dilutions 1/16–1/64
pH
Not stated
Contact time
12 s killing time
Surface / soil
In vitro biofilm

Result: Biofilm impairment at 1/32–1/16 dilution; effective inside the biofilm. Cited for biofilm chemistry only.

BiofilmsBacteriaWound (science only)Lab / in vitro
Sakarya 2014
Source →
PubMed 25785777
Supports activity

Electrochemically generated HOCl vs. drug-resistant biofilm strains

Palau M, Muñoz E, Lujan E, et al. In vitro and in vivo antimicrobial activity of hypochlorous acid against drug-resistant and biofilm-producing strains. Microbiol Spectr. 2022;10(5):e0236522.

Concentration
In situ (20 mA, 20 min)
pH
Not stated
Contact time
20 min
Surface / soil
In vitro; rabbit catheter model

Result: 100% of tested biofilm-producing strains eradicated, including drug-resistant ones.

BiofilmsBacteriaHealthcareLab + animal
Palau 2022
DOI →
PubMed 36190404
Supports activity

Stabilized HOCl on multispecies oral biofilms

Aherne O, Ortiz R, Fazli MM, Davies JR. Effects of stabilized hypochlorous acid on oral biofilm bacteria. BMC Oral Health. 2022;22:415.

Concentration
5 ppm
pH
4.6 (acetic acid)
Contact time
5 min
Surface / soil
Multispecies biofilm; hydroxyapatite

Result: Significantly lower biofilm viability; chlorhexidine showed no equal effect; no hydroxyapatite erosion.

BiofilmsBacteriaDentalLab / in vitro
Aherne 2022
DOI →
PubMed 36127658
Shows limits

Commercial wound solutions on bacterial and fungal biofilms

Harriott MM, Bhindi N, Kassis S, et al. Comparative antimicrobial activity of commercial wound care solutions on bacterial and fungal biofilms. Ann Plast Surg. 2019;83(4):404-410.

Concentration
Commercial products
pH
Not stated
Contact time
1 min to 24 h
Surface / soil
In vitro biofilm

Result: Bacterial biofilms eliminated in 1–10 min, except C. albicans biofilms. Results apply to those regulated products only.

BiofilmsFungi & yeastsWound (science only)Lab / in vitro
Harriott 2019
DOI →
PubMed 31524733
Mixed / conditions matter

HOCl and tissue bacterial bioburden (Part II)

Robson MC, Payne WG, Ko F, et al. Hypochlorous acid as a potential wound care agent: Part II. J Burns Wounds. 2007;6:e6.

Concentration
0.01%
pH
3.5–4.0
Contact time
15–30 min, repeated
Surface / soil
Wound bed

Result: Lowered bioburden (less than silver sulfadiazine) without slowing healing; rapidly neutralized in the wound bed, a clear example of organic load using up HOCl. Science history only.

BacteriaWound (science only)Lab + animal
Robson 2007
Source →
PubMed 17492051
Supports activity

Hypochlorous acid: a review (clinical office)

Block MS, Rowan BG. Hypochlorous acid: a review. J Oral Maxillofac Surg. 2020;78(9):1461-1466.

Concentration
—
pH
—
Contact time
—
Surface / soil
Review

Result: Short clinical review of HOCl chemistry and uses.

Multiple / reviewDentalReview
Block 2020
DOI →
PubMed 32653307
Mixed / conditions matter

Electrolyzed water in the food industry

Rahman S, Khan I, Oh DH. Electrolyzed water as a novel sanitizer in the food industry: current trends and future perspectives. Compr Rev Food Sci Food Saf. 2016;15(3):471-490.

Concentration
—
pH
—
Contact time
—
Surface / soil
Review

Result: Broad food-industry review; candid that acidic EW showed limited efficacy depending on surface, organic matter and water.

Multiple / reviewFoodReview
Rahman 2016
DOI →
PubMed 33401818
Supports activity

HOCl as a potential wound care agent: Part I (chemistry)

Wang L, Bassiri M, Najafi R, et al. Hypochlorous acid as a potential wound care agent: Part I. J Burns Wounds. 2007;6:e5.

Concentration
—
pH
pH speciation
Contact time
—
Surface / soil
Review

Result: Chlorine speciation by pH: HOCl dominates at pH 3–6; Cl₂ gas below ~3.5; OCl⁻ begins forming above ~5.5. Core pH-chart source.

Multiple / reviewGeneral / labReview
Wang 2007
Source →
PubMed 17492050

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