The individual and combined solubilities of hydrogen chloride and sulphur dioxide in xylene and acetonitrile, respectively, have been measured in the temperature range 50-75degreesC and at atmospheric pressure. The apparent heat of solution has also been evaluated. It has been found that, in the presence of HCl, the solubility of SO2 is reduced by approximately 50% at 65 and 60% at 75degreesC. The heat of solution gives results which are in line with the calorimetric measurements on the o-chlorination of 2-nitrobenzoic acid. The solubility measurements also gave consistent results with the calorimetrically obtained gas evolution data at 65 and 75degreesC.