A new hydrate model distinguished from the well known van der Waals-Platteeuw-type model has been developed on the basis of a more reasonable description of the mechanism of hydrate formation. The new concepts proposed include : local stability, linked cavity, basic hydrate, and basic hydrate component (for mixtures). The corresponding thermodynamic model derived has been extensively tested by prediction of hydrate formation from pure gases and gas mixtures. Comparison with experimental data reported in the literature and predictions based on a typical VDW-P-type model indicate that the new model is capable not only of improving prediction accuracy, but also of explaining some intriguing experimental observations in hydrate formation.