A SETARAM C80 calorimeter was used in the experiment to measure the enthalpy of dissolution and thermodynamic properties of trinitrophloroglucinol (TNPG) dissolved in deionized water (H₂O) at 298.15 K. The empirical formula for the enthalpy of dissolution was calculated by polynomial expressions. The fomula is: Δ_dissH_m=106.799266-2352.19194b^1/2+15538.58581b. The standard molar enthalpy of dissolution, the relative apparent molar dissolution enthalpy and the relative partial molar enthalpy also were obtained from the experimental data of the enthalpy of dissolution of TNPG in water. The kinetic formula was obtained. From the formula the rate constant and reaction order are deduced.