A general expression is derived for the supersaturation for crystallization of one-component gas hydrates in aqueous solutions. The supersaturation is the driving force of the process. since it represents the difference between the chemical potentials of a hydrate building unit in the solution and in the hydrate crystal. Expressions for the supersaturation are obtained for solutions supersaturated in isothermal or isobaric regime. The results obtained are applied to the crystallization of hydrates of methane, ethane and other one-component gases. (C) 2002 Elsevier Science B.V. All rights reserved.