The targe positive heat capacity change is a common feature of both the transfer of nonpolar compounds to water and the temperature-induced denaturation of globular proteins, in this paper we present a model for the calculation of the denaturation heat capacity change, that is a key parameter of protein thermodynamics, by means of a simple group additivity scheme and some common structural properties of globular proteins. The specific polar and nonpolar contributions to the heat capacity change are determined by analyzing the transfer of several different series of organic compounds to water. Additionally, we derive a general relationship for the evaluation of the fraction of accessible surface area buried in the protein interior, whose knowledge is necessary because only the groups that contact water on unfolding contribute to the heat capacity change. The model, despite its simplicity, works well, as the agreement between the calculated and experimental values of the denaturation heat capacity change is satisfactory for a large set of globular proteins.