The molar volume and compressibility of (glycylglycine + CuCl2) in aqueous ethanol mixtures have been obtained at four different temperatures T = (28815 to 318.15) K from ultrasonic velocity and density measurements. Excess molar volumes were found to be negative throughout the composition range indicating notable changes in hydrogen bonding and electrostatic interactions. Using the Prigogine-Flory-Patterson theory, quantitative estimation of different contributions, i.e. interactional, free volume, and P* effect to V-E have been obtained. The molar isentropic compressibility has been computed using the ultrasonic velocity and excess volume data. The trends in K-S(E) are affected by the size of the molecule leading to negative contributions. In order to compare the theoretical values of ultrasonic velocity, the equations of Nomoto and Junjie were used and found to predict the experimental data very well. (C) 2011 Elsevier Ltd. All rights reserved.