Hypochlorous acid (HOCl) is one of the most effective and least understood disinfectants available today. Despite being produced naturally by the human body, it remains largely unknown outside of scientific and medical circles — yet it outperforms many of the harsh chemical cleaners found in homes and commercial environments.
This article explains what HOCl is, how it works, and why it represents a fundamentally different approach to surface disinfection.
What is Hypochlorous Acid?
Hypochlorous acid is a weak acid formed when chlorine dissolves in water. More significantly, it is the active compound produced by white blood cells (neutrophils) during the immune response — your body's own mechanism for neutralising bacteria, viruses, and other pathogens at the cellular level.
At a molecular level, HOCl carries no electrical charge, which allows it to penetrate the cell walls of microorganisms far more effectively than charged compounds like sodium hypochlorite (bleach). This is what makes it so potent as a disinfectant — and so gentle on everything else.
How Does HOCl Work as a Disinfectant?
HOCl works by disrupting the cellular machinery of pathogens. When it comes into contact with bacteria or viruses, it oxidises proteins and lipids in the cell membrane, causing irreversible damage that neutralises the microorganism.
This mechanism is effective against a broad spectrum of pathogens including:
- Bacteria (including MRSA and E. coli)
- Viruses (including enveloped viruses)
- Fungi and moulds
- Biofilms
Crucially, HOCl achieves this at concentrations that are non-toxic to humans and animals. At 500ppm of free available chlorine — the concentration used in Optizan® — it delivers broad-spectrum disinfection without the harmful residues associated with bleach or the flammability risks of alcohol-based products.
Why is HOCl pH Neutral?
The effectiveness of HOCl is closely tied to pH. At a neutral pH (around 6.5–7.5), the majority of available chlorine exists as HOCl rather than the less effective hypochlorite ion (OCl⁻). This is why pH-neutral formulations like Optizan® are significantly more effective than alkaline bleach solutions at equivalent chlorine concentrations.
HOCl vs Bleach vs Alcohol
| HOCl | Bleach | Alcohol | |
|---|---|---|---|
| Toxic residue | None | Yes | No |
| Flammable | No | No | Yes |
| pH neutral | Yes | No (alkaline) | No |
| Requires rinsing | No | Yes | No |
| Broad-spectrum | Yes | Yes | Yes |
| Non-scented | Yes | No | No |
What Happens After HOCl is Applied?
One of HOCl's most important properties is what happens after it has done its job. Unlike bleach, which leaves behind sodium hydroxide residues, HOCl breaks down into water and a trace amount of salt — leaving no toxic byproduct on the surfaces it treats. This makes it suitable for food preparation areas, children's environments, and anywhere that residue-free disinfection matters.
Why Isn't HOCl More Widely Used?
Until recently, producing stable HOCl at effective concentrations was technically challenging. Early formulations degraded quickly and were difficult to store. Advances in electrochemical production and stabilisation technology have changed this — making it possible to deliver HOCl at consistent, effective concentrations with a commercially viable shelf life.
Optizan® is formulated to maintain 500ppm of free available chlorine throughout its shelf life, ensuring consistent performance from first use to last.
For a detailed comparison of HOCl against bleach and alcohol-based disinfectants, see our guide: Hypochlorous Acid vs Bleach vs Alcohol: Which Wins?
Summary
Hypochlorous acid is a naturally occurring, non-toxic disinfectant that works by oxidising the cell membranes of pathogens. It is pH neutral, leaves no toxic residue, and is effective against a broad spectrum of bacteria, viruses, and fungi. At 500ppm, it delivers professional-grade disinfection without the risks associated with bleach or alcohol-based alternatives.