Oxy-hydrogen welding is a gas welding process in which the required welding temperature is attained by flames obtained from the combustion of hydrogen with oxygen.
The use of oxygen and hydrogen as the gases for welding and cutting is older than the oxy-acetylene process and dates back to before the production of oxygen by either electrolysis or liquefaction of air. Oxygen was probably generated in those days from potassium chlorate and manganese dioxide, or perhaps from potassium and sodium peroxides and water, and the hydrogen from hydrochloric acid and zinc. The oxy-hydrogen process was developed by Newman who used detonating gas (pure oxygen and hydrogen mixed) at a pressure of about 3 atmospheres. This gas is still used to some extent in welding platinum, lead, and precious metals but it is rapidly being superseded by apparatus designed to use the oxygen and hydrogen from separate cylinders.