The dissolution enthalpy of sodium sulfate in water was measured until saturation at 24.4, 27.5 and 44.3 degrees C using a C80D differential calorimeter (Setaram). The experimental data were fitted using Pitzer’s ion interaction model and the value of the dissolution enthalpy per mole of salt at infinite dilution was found at each temperature, by treating (Delta(diss)H)(infinity) as an adjustable parameter.