(Surfactant + polymer) systems play an important role in drug delivery. They control the drug release rate by improving solubility, minimizing degradation, contributing to the reduction of toxicity and facilitating drug administration. Physicochemical properties of surfactant/polymer systems used in controlled drug release are affected by the composition of the mixture. The study of the physicochemical behavior of these mixtures allows the design of more suitable drug pharmaceutical formulation according to its chemical structure. In this paper, critical micelle concentration (CMC), saturation concentration (C-2), critical aggregation concentration (CAC) and thermodynamic parameters, such as enthalpy (Delta H), Gibbs free energy (Delta G) and the temperature multiplied by entropy (T Delta S) for the demicellization process were determined by isothermal titration calorimetry (ITC), for octyl-beta-D-glucopyranoside (OGP) and hydroxyethyl-cellulose (HEC) aqueous solutions in order to construct a phase diagram suitable for the study of the interactions in each region and to choose the appropriate system for drug delivery. The interpretation of the results is supported by the analysis of particle size measurements by dynamic light scattering (DLS). (C) 2014 Elsevier Ltd. All rights reserved.