The enthalpy of dilution in the sodium sulfate-water, ammonium sulfate-water and ammonia-water systems was measured at temperatures from 313 to 373 K with a Calvet-type batch calorimeter using specially designed mixing cells. The mixing cells allow to pressurize the solutions. The formation of a gas phase during the experiments is thus avoided. Experimental results for the enthalpy of dilution are reported and compared to literature data and correlations.