The objective of this work was to study the hydrolysis kinetics and also the character of the involvement of the epoxidation catalyst (Na2WO4 - sodium tungstate) on the hydrolysis of cis-epoxysuccinic acid (the initial product in the hydroxylation reaction of maleic acid by hydrogen peroxide). The results obtained at 65 degrees C clearly revealed that the hydrolysis reaction exhibits a considerably low rate in the absence of a catalyst whilst the rate is significantly enhanced by the introduction of catalytic quantities of Na2WO4. The phenomenon of end-product inhibition was observed in this study and the results obtained permitted the development of a kinetic model consistent with experimental observations. Analysis of the kinetic model shows that the reaction is first order with respect to the concentrations of the catalyst and the epoxide. However, tartaric acid has a strong inhibitive influence on the overall reaction rate.