This paper proposes a study of different cation exchange resins, used as catalysts for the synthesis of peroxypropionic acid (PPA) from propionic acid and hydrogen peroxide at 40 degrees C, equimolar concentration of reactants and an apparent Bronsted concentration of 0.2 M. The catalytic activities of the resins are on the same scale as sulfuric acid at comparable concentration level and decrease in the order: Dowex 50Wx2 > Smopex-101 > Dowex 50Wx8 approximate to Amberlite IR-120 > Amberlyst 15. The influence of external and internal mass transfer limitation was evaluated. The experiments also demonstrated that a gelular resin with a degree of cross-linking equal to 8% and a particle size of more than 0.1 mm showed a stronger resistance to deactivation. (C) 2008 Elsevier B.V. All rights reserved.