The cross-linking and foaming processes of ethylene vinyl acetate (EVA) copolymer with different concentrations of polyethylene (PE), cross-linking agent (alpha-alpha'-bis(tert-butylperoxy)-m/p-diisopropylbenzene), and azodicarbonamide (as foaming agent and using additionally ZnO as accelerating agent) have been studied. The extent of the reactions has been evaluated by gel fraction and density measurements. The different transitions involved in the thermal processing and decomposition have been studied by DSC and TGA and compared for all the mixtures prepared. Mechanistic pseudokinetic models have been suggested and applied involving all the fractions susceptible of undergoing transitions or reactions, including complex, overlapped peaks and apparent heat capacities. The models applied can be of great interest in understanding the phenomena involved, as well as in modeling the heat effects in the whole processing or pyrolysis of this type of multicomponent products.