Measurements of the spin-lattice relaxation times,T1, for the75As nucleus are presented for solutions of potassium hexafluoroarsenate in diethyleneglycol dimethylether (diglyme) over the temperature range 306·7–363·2°k. Values ofT1are also given for solutions of the silver and tetra-n-butylammonium salts in acetonitrile and acetone respectively, at 293·2°ktogether with values for solutions of various mixtures of salts. Density and viscosity data are given for each solution. The slopes of (T1)-1against viscosity/temperature graphs are found to be independent of solution composition for a given salt and solvent but are functions of temperature and cation. Solvation data, calculated from the viscosity and density measurements, together with the effects of cation and temperature on the relaxation rates indicate that relaxation is probably caused by cation-anion interactions. It is suggested that the relaxation is brought about by a short range interaction, which at any given instant is being experienced by an approximately concentration independent fraction of the arsenic nuclei.