We have developed the complete thermodynamic property fields for a single-component adsorbent + adsorbate system. These equations enable us to compute the actual specific heat capacity, the partial enthalpy, and the entropy, which are essential for the analyses of single-component adsorption processes. Conventionally, the specific heat capacity of the adsorbate is assumed to correspond to its liquid phase specific heat capacity and more recently to that of its gas phase. We have shown that the actual specific heat capacity of the adsorbate could differ significantly from what has been conventionally assumed. A simple but improved expression for the adsorbate specific heat capacity is also proposed.