Peroxycarboxylic acids are widely used in industry for disinfection and bleaching as well as fine chemistry. The synthesis of peroxycarboxylic acid from carboxylic acid and hydrogen peroxide is a reversible reaction. Due to the slow kinetics of this reaction, acid catalysts are needed. This paper describes a kinetic study of carboxylic acids perhydrolysis in the presence of sulphuric acid at various molar reactant ratios, reaction temperatures and catalyst concentrations. The influence of water and acidic catalysts were taken into account to develop a plausible kinetic model. A “greener” way of peroxycarboxylic acid synthesis using solid acid catalysts was investigated. Cation exchange resins showed a higher catalytic activity than aluminosilicates under comparable experimental conditions. A general model was developed, comprising the kinetic and mass transfer effects in porous catalyst particles (i.e., Amberlite IR-120) in batch reactors. The concentrations in the bulk phase and inside the catalyst particles were predicted by the model. The stability of peroxycarboxylic acid was investigated. Decomposition of peroxycarboxylic acid takes place in the liquid phase, but products of decomposition, carbon dioxide and oxygen are transferred to gas phase. An analytical method was developed to determine the decomposition of the peroxycarboxylic acid in the liquid phase by means of chemical analysis of the gas phase. The method is based on on-line mass spectroscopy (MS). A mathematical model for the semi-batch gas-liquid system was developed.