An epoxy based on the diglycidyl ether of bisphenol A (DGEBA) has been modified with poly(ether imide) (PEI) and cured with 1,3-bisaminomethylcyclohexane (1,3-BAC). The curing kinetics of the neat resin and of a PEI/epoxy blend were analysed and compared by differential scanning calorimetry. The results showed that the PEI has effect on curing reaction, reaching less conversion in this process than for the neat system. The experimental data for both systems showed an autocatalytic behaviour and the phenomenological model of Kamal was proposed to obtain the activation energies for the rate constants. The values of the activation energies for the PEI/epoxy blend system are higher than the values for the neat system. Diffusion control is incorporated to describe the cure in the latter stages predicting the cure kinetics over the whole range of conversion.