A method based on the mixing calorimetry for determination of hydrate dissociation heat was introduced. Under the condition of atmospheric pressure, the dissociation heat of tetrahydrofuran (THF) hydrate, which was about (275.62  2.64) kJ/kg at 4.4 C of phase-transition temperature, was determined by this method. Similarly, the dissociation heat of CH3CFCl2¬ (HCFC-141b) hydrate was about (348.48  3.08) kJ/kg at the phase-transition temperature of 8.4 C. By comparison with those previous results, the maximum relative error is 2% and 6.6%, respectively. To obtain the optimal results of dissociation heat, the mass ratio between hot water and THF hydrate or HCFC-141b hydrate has been optimized as well.