More physically-based models are used when developing the third generation Calphad descriptions, which en -able to calculate and predict the thermodynamic properties with higher reliability in an extended temperature range. In order to examine the unary descriptions and verify the models for developing binary descriptions, the W-C binary system was selected as test vehicle. The description of liquid C was first re-assessed adopting the most recent suggestion on modelling the liquid phase. The Einstein/Neumann-Kopp model (the hybrid model) was applied to model all the end-members of the solid solution phases. This work further verifies the hybrid model and the method used to extrapolate the solid data of pure W.