Liquid densities of several binary aqueous electrolyte mixtures and mixtures containing methanol and electrolytes were measured over a large range of concentrations and temperatures from 283 to 353 K using an oscillating-tube densitometer. From these values, molar volumes were calculated for all experimental data. A new empirical correlation method was introduced to determine densities and molar volumes using only two additional parameters, which were fitted for all ionic species investigated in this work. The experimental and calculated results are presented in comparison to results of other authors.