Measurement of the solubility of HCl gas in ZnCl 2 +NaCl binary molten mixtures has been carried out by an elution technique. The solubility data were found to exhiibit trends characteristic of a chemical dissolution process, implying the formation of a complex species. It is suggested that as the melt basicity is increased the predominant species changes from a coordinated zinc species to HCl 2 - , with the more basic melts tending toward behavior exhibited by HCl in pure molten alkali-metal chlorides