Highlights
- Hypochlorous acid (HOCl) was discovered in 1834 by French chemist Antoine Jérôme Balard.
- It occurs naturally in the human body as part of the immune system.
- Early studies showed it was powerful against germs yet gentle on living tissue.
- In the 1800s, HOCl was tested in sanitation and public health experiments.
- Instability limited its practical use until new methods were developed.
- HOCl later became essential in WWI wound care and modern cleaning.
A Discovery That Changed Science and Medicine
When people today ask what is hypochlorous acid, they often hear it described as a safe and powerful disinfectant spray. But almost two centuries ago, a French chemist named Antoine Jérôme Balard was the first to identify this remarkable compound. His work in 1834 marked the beginning of a long history of science, medicine, and public health that still continues today.
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Antoine Jérôme Balard: The Chemist Who Discovered HOCl
In 1834, Balard — already famous for discovering the element bromine — turned his attention to chlorine chemistry. Through careful experiments, he isolated a weak acid formed when chlorine dissolved in water. He named it acide hypochloreux, or hypochlorous acid.
Balard could not have known then that his discovery would one day be used in hospitals, on battlefields, and in households around the world. Still, his research laid the foundation for nearly 200 years of exploration into how this acid could fight germs.
Early Curiosity: Defining What Hypochlorous Acid Is
So, what is hypochlorous acid? Chemically, it’s written as HOCl. It is formed naturally in our own immune systems, where white blood cells produce it to destroy bacteria and viruses. In the lab, it can be generated by dissolving chlorine in water or by modern electrolysis methods.
Even in the 1800s, scientists realized HOCl was unique. Unlike harsh disinfectants such as carbolic acid, it was powerful against germs but gentle on living tissue. This raised early hopes that it could be used in medicine and sanitation.
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Why 19th-Century Medicine Needed Better Disinfectants
During the 1800s, Europe faced deadly outbreaks of cholera, typhoid, and other infectious diseases. Hospitals struggled with infections, and surgeons had few safe antiseptics to use. While Balard’s discovery was promising, HOCl’s instability limited how far it could spread into practice. Solutions would break down quickly, and the science of infection control was still developing.
Still, references to HOCl began appearing in sanitation experiments, and public health authorities started testing chlorine-based solutions in water supplies. Balard’s discovery had planted a seed that would grow stronger in the decades ahead.
The Foundations of a Safer Future
By the end of the 19th century, doctors and scientists were searching for antiseptics that could fight infections without causing harm. HOCl was increasingly recognized as one of the most powerful tools available — even if it wasn’t yet practical for everyday use.
That would change in the 20th century. When World War I arrived, hypochlorous acid was rediscovered as an effective disinfectant spray for treating wounds on the battlefield. The breakthrough research published in 1915 by Edinburgh scientists proved that HOCl was not just a laboratory curiosity — it was a life-saving antiseptic.
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Sources
- Antoine Jérôme Balard – discovery of hypochlorous acid (1834) — concise history with primary citations to Balard’s 1834 paper.. Wikipedia
- CDC: Chemical Disinfectants (Guideline for Disinfection & Sterilization) — explains that chlorine’s microbicidal activity is largely due to undissociated hypochlorous acid (HOCl). CDC