Decomposition conditions of methane hydrate in marine sediments from South China Sea were measured using multi-step decomposition method. Four different samples of the marine sediments were used in the experiments. The pore distribution, the surface area, particle size and the surface texture were measured and observed. The experimental results indicated that the final decomposition temperatures are shifted lower than those for bulk hydrates at the same pressure for different marine sediments and different water saturations. Temperature shifts are more negative for smaller initial water saturation. The surface textures and pore of the sediments both affect the equilibrium condition of methane hydrate. Using the Clausius-Clapeyron equation, the enthalpy of hydrate dissociation in marine sediments was calculated. It was found that the enthalpy of hydrate dissociation in marine sediments with lower water saturation is higher than that at the bulk state. (C) 2015 Elsevier B.V. All rights reserved.