Brillouin scattering studies have been carried out in a number of aqueous electrolyte solutions at various concentrations up to 4M. Two types of results have been obtained: (1) hypersonic velocity data from the frequency shift of the Brillouin components; and (2) hypersonic absorption coefficients from the line widths of the Brillouin components. The results compare favorably with those from ultrasonic velocity and absorption data at lower frequencies.