Through swelling experiments on polyelectrolyte (HEMA/DMA) hydrogels, pH-induced swelling kinetics is found to be best described by a diffusion-mechanical relaxation incorporated model. The theory of equilibrium swelling is quantitatively combined into the model of swelling kinetics. By doing so, the advantage is taken of applying relatively more matured knowledge of gel swelling thermodynamics to predict less knowledgeable dynamic behavior of gels.