The transient heat transport property of conduction calorimeter is dissected and the experimental time-dependent cooling constant model of the conduction calorimeter is established in this paper. The thermal relaxation method proposed in this paper can be used to determine the faster reactions whose first-order rate constant could be less than 5 s^-^1 with the calorimetric technique. In order to test the validity of this method, the saponification of methyl acetate, ethyl formate and methyl formate in aqueous solution at 25℃ has been studied. The rate constants calculated with this method are in agreement with those in the literatrues. Therefore, the thermal relaxation method is believed to be correct.

Key words: THERMODYNAMICS, RELAXATION, METHYLACETATE, ETHYL FORMATE, FORMIC ETHER, SAPONIFICATION