A preliminary mass spectrometric study has been carried out on salt vapours in equilibrium with both solid and liquid CdCl2, CsCl, PbCl2, and the salt systems CdCl2 + RbCl, CdCl2+ CsCl, PbCl2 + RbCl, and PbCl2 + CsCl. The results are interpreted to indicate the existence of complex molecules of the type AMCl3 in the salt systems studied (where A is an alkali metal and M is a divalent metal).