An ideal, hydrated, nondilute pseudo-binary solution model is presented to describe the concentration polarization of solutes within cells during osmotic experiments. This model has been applied to the case of hyman erythrocytes being cooled at subzero temperatures. The concentration polarization of solutes within the RBC intracellular solution during freezing reveals the fact that the water transport process is significantly affected not only by the permeation of water through the cell membrane, but also by the diffusion of water within the intracellular medium.