Abstract: Peracetic acid in aqueous liquid solution or vapor phase is prepared on-site and on-demand in a continuous process. Peracetic acid can be produced at a controlled rate to meet the demands of a downstream operation. In one embodiment, a pipe-line reactor and distillation column is used for the production of peracetic acid. In another embodiment, an apparatus includes a continuous pot reactor and distillation column for producing peracetic acid. The present invention has the potential of providing a much safer source of aqueous peracetic acid than currently available processes, due in part to the limited inventories of reactants in the reactor, particularly those in the vapor phase.