The effect of three dissolved salts namely sodium chloride, calcium chloride and zinc chloride on the heat of mixing (endothermic) of the binary system 2-propanol-benzene has been experimentally investigated. The salts were dissolved in the component in which they were preferentially soluble to concentrations up to 15% by weight wherever possible. The experimentation was done at 30-degrees-C using a standard type calorimeter attached to a micro-processor based control unit MIPROC. The established experimental procedure was followed. The salts sodium chloride and zinc chloride brought about an enhancement in the heat of mixing values. Calcium chloride on the other hand has been found to produce an opposite effect.