Critical assessment of the thermodynamic data for pure copper was carried using careful analysis of the existing experimental data. An extended Einstein model was used for the crystalline phase and the two state model was applied for the liquid phase. Special attention is paid in this work to the precise description of the following thermodynamic functions: So298, Ho298–Ho0, the melting temperature, and the entropy and enthalpy of fusion. In order to fullfill the need for a precise evaluation of So298 we needed to use an additional technique, which allows the experimental heat capacity and enthalpy data for the solid phase to be approximated accurately from 0K up to the melting point. Relative stabilities of the BCC_A2 and HCP_A3 phases were derived.