The dilution enthalpies of NiCl2 aqueous solution were experimentally determined from nearly saturated to different molalities at T = ( 298.15, 308.15 and 318.15) K. Combined with evaluated literature data, an expression of Pitzer-Archer activity coefficient parameters with temperature was deduced based on the Pitzer-Archer model and the basic thermodynamic relation among activity coefficient, enthalpy and heat capacity, which was used to calculate the activity and osmotic coefficients of NiCl2 aqueous solution at a certain range of temperature. (C) 2016 Elsevier Ltd. All rights reserved.