Production of peroxycarboxylic acids

Provided are various methods, systems and reactors for producing peroxycarboxylic acid compositions, such as non-equilibrium compositions of peracetic acid, for example. The methods and systems relate to electrolytic generation of hydrogen peroxide or peroxide ions in a reactor, wherein the generated materials are reacted with an acetyl donor to form peracetic acid. In an embodiment, a source of alkali metal ions is provided to an anode chamber such that the ratio of concentrations of the alkali metal ions to protons in the anode chamber of a reactor is greater than 1.