A systematic thermo-physical characterization of the Europium and Europium-Hen Egg's White (HEW) Lysozyme in the ternary system at T = (313.15.15, 323.15.15) K and atmospheric pressure was elucidated. Thus, density (rho), viscosity (eta) and ultrasonic sound velocity (U) and thereby various acoustical and thermodynamic parameters have been determined. Moreover, a comparison between experimental results for the pure system and solutions of Europium and Europium-Lysozyme (HEW) studies has been carried out to analyze carefully how the structural modifications affect the values of Gibbs free energy of activation (Delta G), enthalpy of activation (Delta H) and entropy of activation (Delta S) in DMF. (C) 2013 Elsevier Ltd. All rights reserved.