Solution densities have been determined for aqueous solutions of the tripeptides of sequence glycyl-X-glycine, where X is one of the amino acids alanine, valine, leucine, isoleucine, phenylalanine, methionine, and proline, at T = (288.15, 303.15, and 313.15) K. These solution densities were used to calculate the partial molar volumes at infinite dilution, V-2 degrees, for the tripeptides. The V-2 degrees results were combined with those determined in previous work for T = 298.15 K to obtain the partial molar isobaric expansions at infinite dilution, E-2 degrees{E-2 degrees = (partial derivative V-2 degrees/partial derivative T)(p)}, forthe tripeptides at T = 298.15 K. The contribution of amino acid side-chain hydration to the E-2 degrees results has been discussed. (C) 2009 Elsevier Ltd. All rights reserved.