A study of the temperature dependence of relative viscosity \(\eta_1/\eta_0\) of concentrated and supersatura ted aqueous solutions of electrolyte, has been made. The reunite show that, provided viscosity remains sufficiently low, \(\delta/\delta_t(\eta_1/\eta_0)\) is positive even in highly concentrated solutions of some electroly­tes e. g. KCl, KBr and KNO3 etc. Further, the \(\delta/\delta_t(\eta_1/\eta_0)\) is comparatively much high in the solutions of substances which have law hydrating power as compared to those which easily form hydrates with water molecules. These observations have been explained with the help of Rabinowitsch's hydrate hypothesis and the depolymerisation concept of Applebey.