Block copolymers are a special class of polymers having the ability to self-assemble into nanoscale ordered structures which depend on molecular composition of the blocks. With the aim of studying the influence of copolymer composition, the kinetics of a 4,4′-diaminodiphenylmethane-cured diglycidyl ether of bisphenol-A (DGEBA) epoxy system modified with a PEO-PPO-PEO block copolymers has been investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), taking into account the relation between blocks in the copolymer as well as different copolymer contents. DSC results show that the rate of cure reaction decreases when the copolymer is added, which can be attributed to the interaction between the hidroxyl groups of the growing epoxy thermoset and the ether groups of the block copolymer observed by FTIR. The experimental results obtained have been related to the morphologies observed by atomic force microscopy (AFM).