A method was developed and implemented for predicting enthalpies of gas hydrate formation, which are required for the efficient design of gas hydrate-based processes. The proposed method is based on the statistical thermodynamic theory of solid solutions and it is thermodynamically consistent. It allows delineation of the various energetic contributions, does not resort to empirical constants enforced by regressions anti applies to any simple or multicomponent bulk hydrate equilibrium system at the hydrate point or beyond it. The application of the method was demonstrated for several simple, double and multicomponent gas hydrate systems with one or two equilibrium hydrate phases. It was found that a major energetic component in hydrate formation is the heat of enclathration, defined as the residual enthalpy of the enclathrated gas. All example applications indicated that this property is a constant, independent of temperature, pressure and composition, characteristic only of the individual gas and it was regressed by a general corresponding states analytical expression. (c) 2005 American Institute of Chemical Engineers