Englezos et al. have proposed an intrinsic kinetic model for the growth of gas hydrates. An analysis of the model has been performed. Based on this analysis and data on hydrate formation from methane and ethane in a semi-batch stirred reactor measured by Bishnoi et al., a simplified model is proposed. The simplified model is based on the assumption that the transport of gas molecules from the gas phase to the liquid water phase is the rate-determining step in the overall hydrate formation process. Comparisons with the experimental data show that a simple film theory model for mass transport can adequately reproduce the experimental data. Calculations also show that a correct calculation of the driving force is important, especially when the driving force is small.