Hydrogels with four different plant-based microcrystalline cellulose concentrations were prepared using the self-assembly technique. The interaction parameter between cellulose and water was determined by the classical Flory-Huggins theory, and was found to be around 0.44 with weak concentration dependence. The crosslinking density in these hydrogels was measured by both the Mooney-Rivlin equation and the Flory-Rehner theory. Reasonable consistency was found between the two methods albeit results from the Flory-Rehner theory were slightly higher due to the contribution from the physical crosslinks. The crosslinking density values for all four hydrogels determined from both methods were found to range from 19 to 56 mol/m3. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013