An analysis of the isothermal Cure kinetics of the RSL-1895 epoxy resin/EPON curing agent system supplied by the Shell Development Co. was performed based on polymer cure kinetics and the polymer composite degradation methodology. The model expression describing the isothermal cure kinetics could be derived by Nam and Seferis based on hypothesis that the elementary reactions of epoxy systems can be linearly combined with the weighting factors. The resulting kinetic model equation for the epoxy system was as follows. dα/dt = k(T) [y(1)(1-α) + y(2)α(m) (1-α)(n)] The isothermal DSC data were in good agreement with the predictions by the above model equation used in this study using kinetic parameters determined from the kinetic analysis. The model expression of the isothermal cure kinetics proposed in this study is expected to be utilized in simulations of the cure processes of fiber reinforced composites employing the RSL-1895/EPON W epoxy resin system.