Apparent molar volumes V_Φ of glycylglycine in aqueous KCl and NaCl solutions have been obtained from densities at 298.15 and 308.15 K measured with a vibrating-tube densimeter. These data have been used to deduce partial molar volumes of transfer Δ_trsV_Φ^? from water to different salt water mixtures. Δ_trsV_Φ^? values are positive. This result arises from the interaction of KCl and NaCl with the charged centers of glycylglycine. The positive Δ_trsV_Φ^? of glycylglycine shows that salts in the concentration range studied will stabilize the globular protein. The results show that Δ_trsV_Φ^? depends less on temperature. The interaction between the charged centers of glycylglycine and ions dominates other forms interactions. The results have been explained using the cosphere overlap model.

Key words: limiting partial molar volume, glycylglycine, electrolyte