The thermal behavior of several formulations consisting of ethylene-propylene elastomers and acrylonitrile-butadiene rubber was investigated by differential scanning calorimetry. The sample compositions cover the whole concentration range of ((EPDM, EPR)/NBR = 100/0, 20/80, 40/60, 60/40, 80/20 and 0/100). The evaluation of molar enthalpies for studied polymer blends allowed to calculate molar capacities at various temperatures from 335 K up to 450 K. Due to the lack of additivity in the molar capacities of studied blends, the contributions of each component to the overall values of C-p are calculated. The dependency of component contributions on their concentrations follows a first order function, which explains the existence of a certain interaction between components.