Chitosan hydrogels were cross-linked with glutaraldehyde and examined for the adsorption of a model protein (bovine serum albumin, BSA) at different pH and cross-linking ratios. It was observed that the cross-linking significantly improved the chemical and structural stability of the hydrogel beads. The adsorption equilibrium was described by the Langmuir isotherm. The optimal adsorption capacity was identified at the cross-linking ratio of 0.2 and a pH of 5.5. The cross-linked chitosan hydrogels as well as BSA adsorbed chitosan hydrogels were characterized, and based on that, the adsorption mechanisms were discussed.