This report describes the evaluation and enhancement of the enthalpy model developed for the SRC-I process (as well as other coal liquefaction processes). The enthalpy model has been described in a previous report (Mathias and Monks, 1982). A key feature of the model is the proposed extended corresponding-states framework, obtained through the introduction of a new parameter, termed the polar parameter. It is usual practice to treat the essentially continuous coal-fluid mixture as a set of pseudocomponents, each defined by a narrow range in normal boiling point. The model developed by Mathias and Monks (1982) characterizes each pseudocomponent with the normal boiling point, specific gravity, and polar parameter. Mathias and Monks found that the model provided an excellent description of existing coal-fluid enthalpy data - if the polar parameter was chosen to best fit the data. However, use of the model in process design requires a predictive method for the polar parameter. ICRC is conducting a program to obtain enthalpy measurements in order to provide verification of the current design conditions for the SRC-I Demonstration Plant and data for developing reliable correlations (Mehta, et al., 1983). A majority of the data has been received, analysis of which is described in this report. Comparison of the model to data on three SRC-I 50/sup 0/F boiling fractions indicates, again, that the data is well correlated if the optimum value of the polar parameter is used. More importantly, this analysis has provided a reasonable basis to predict the values of the polar parameters for all the pseudocomponents employed in the simulation of the SRC-I process. The proposed model has provided encouraging agreement with experimental data, but final conclusions must await analysis of the entire set of data.