This study examined the effect of the polymer solution concentration on the swelling and mechanical properties of glycol chitosan (GCS) superporous hydrogels (SPHs). GCS SPHs were synthesized using a gas blowing method using glyoxal as the crosslinking agent at different polymer solution concentrations. A small change in the GCS solution concentration resulted in a remarkable change in compression strength and swelling kinetics without any significant loss in equilibrium water imbibing capacity. The increase in mechanical strength accompanied by the decrease in swelling kinetics was caused by the generation of smaller pores during the gelation process of the reactant systems associated with a higher polymer solution viscosity. The apparent diffusion coefficients for a variety of GCS/simulated gastric fluid solution systems were determined from the theoretical fitting of experimental dynamic swelling data, explaining the effects of the solution concentration and crosslinking density on the swelling kinetics. The diffusion coefficients determined in this study are expected to be used as the basic information in estimating the swelling kinetics of samples in different dimension. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 3434-3441, 2010