LiNO3-[EMIM][DEP] (1-Ethyl-3-methylimidazolium diethylphosphate)/H2O has been suggested as an alternative working pair for absorption heat pump. The thermophysical properties including crystallization temperatures, densities, viscosities, specific heat capacities, dissolution enthalpies, and thermal diffusivities for this ternary system with a mass ratio (LiNO3:[EMIM][DEP]) of 3:1 were measured. The crystallization temperatures were measured from w = 0.60 to w = 0.74. The densities, viscosities and specific heat capacities were measured at absorbent mass fractions from w = 0.55 to w = 0.70 and temperatures from 303.15 K to 373.15 K. The dissolution enthalpies were measured from w = 0.55 to w = 0.70 at 313. 15 K. The thermal diffusivities were measured from w = 0.55 to w = 0.70 and 303.15 K to 363.15 K. The specific enthalpy differences and thermal conductivities were calculated based on the measured data. Regression equations for the crystallization temperatures, densities, viscosities, specific heat capacities, specific enthalpy differences and thermal conductivities were obtained by a least-squares method. The average absolute relative deviations between the measured data and the calculated data were 0.36%, 0.03%, 0.82%, 0.11%, 0.03% and 0.69%, respectively. These properties were helpful for the calculation and evaluation of the absorption heat pump based on LiNO3-[EMIM][DEP]/H2O. (C) 2018 Elsevier Ltd.