This article describes a kinetic study of the perhydrolysis of propionic acid with sulfuric acid at various molar reactant ratios (PA-H2O2 from 0.4 to 2.05), reaction temperatures (from 30 to 60 degrees C), and catalyst concentrations (from 0 to 1.41 M). The influence of water and acidic catalysts were taken into account to develop a suitable kinetic model. The system is nonideal, mainly due to the presence of the strong electrolyte (i.e., H2SO4), and a parameter was introduced to describe the nonideality. The kinetic and thermodynamic parameters determined by nonlinear regression analysis were statistically well identified. The standard enthalpy change of reaction was estimated to -4.17 kJ.mol(-1), and the activation energy of the reaction was estimated to 44.2 kJ.mol(-1).