Abstract: The production of dilute equilibrium, storage stable solutions of peracetic acid from mixtures of aqueous hydrogen peroxide and acetic acid, or by dilution of more concentrated peracetic acid solutions, takes a long time because of the low concentrations of the active participating materials. The process can be accelerated by employing a two step procedure in which a concentrated peracetic acid solution is diluted with water and partially hydrolysed in the first step, and then the hydrolysis reaction is quenched by addition of hydrogen peroxide in the second step.