In the last few decades, the interest in ion exchange polymers that are able to respond under several external stimuli has grown; these polymers are being used in the most diverse fields of science such as sensors, transducers and actuators. This type of material, when in contact with aqueous solutions, undergoes deformations caused by changes in magnetic fields, temperature, pH, electrical fields and/or ionic strength. Since the pH is a critical operating parameter in the control of different chemical processes, pH sensitive polymers have become a promising alternative in several areas of research and of particular interest in this work in the area of pH monitoring applied to the oil industry. The great potential and functionality of this type of polymers has increased the need to study and understand their behavior through mathematical models. The purpose of this study was to develop a chemo-electromechanical model to study the swelling of an ion exchange resin in equilibrium with an electrolyte solution, as a function of changes in pH and saline concentration of the solution. In order to determine parameters related to the chemical equilibrium associated with the surface electric charge density of resin, potentiometric titrations as well as measures of swelling for three NaCl concentrations were developed. Aiming to investigate the microstructure and composition of the polymer, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) tests were performed. The mathematical modeling was developed in two scales (micromacro) adopting the homogenization technique of periodic structures. For modeling the swelling of the resin, the hypothesis of linear elastic material was assumed, incorporating the electroosmotic phenomena in the local scale through the solution to the Poisson-Boltzmann problem and the balance of linear momentum in the fluid. The system of nonlinear equations placed in the macroscopic scale was discretized through the Finite Element Method (Galerkin) and the coupled equations solved with the method of Newton-Raphson. The theoretical results show the presence of two swelling regimes in the resin: a regime controlled by the charge density on the surface of the solid and a secondary regime where the swelling of the resin is purely governed by the ionic strength of the electrolyte solution.