Densities (ρ) of glycine, alanine and leucine in aqueous solutions of potassium chloride (KCl) (0.01–0.10 mol kg −1 ) have been measured at 310.15 K. Apparent molar volumes (V ϕ ), limiting partial molar volumes (V ϕ 0 ) and group contributions to partial molar volumes have been determined for the amino acids. The trends of transfer volumes (ΔV ϕ 0 ) have been interpreted in terms of solute–cosolute interactions on the basis of a cosphere overlap model. Pair and triplet interaction coefficients have also been calculated from transfer parameters.