Using a dynamic laser monitoring technique， the solubility of 3-nitro-l，2，4-triazole-5-one （NTO） was investigated in two different binary systems， namely hydroxylamine nitrate （HAN）-water and boric acid （HB）-water ranging from 278.15 K to 318.15 K. The solubility in each system was found to be positively correlated with temperature. Furthermore， solubility data were analyzed using four equations： the modified Apelblat equation， Van’t Hoff equation， λh equation and CNIBS/R-K equations， and they provided satisfactory results for both two systems. The average root-mean-square deviation （10⁵RMSD） values for these models were less than 13.93. Calculations utilizing the Van’t Hoff equation and Gibbs equations facilitated the derivation of apparent thermodynamic properties of NTO dissolution in the two systems， including values for Gibbs free energy， enthalpy and entropy. The %ζ_H is larger than %ζ_TS， and all the %ζ_H data are ≥ 58.63%， indicating that the enthalpy make a greater contribution than entropy to the ΔG_soln^o.