The thermodynamic properties of the dielectric materials are analyzed in detail, based on the Curie law, Curie-Weiss law and other relations between the electrical polarization and the electric field strength. It is proven that the specific heat at constant electrical polarization is only a function of temperature, while the specific heat at constant electric field strength is dependent on the electric field strength and temperature. Moreover, the regenerative characteristics of the electrocaloric Stirling and Ericsson refrigeration cycles are discussed. Some important conclusions are obtained.