Chitosan hydrogels were prepared and imprinted by Ag-I with different mass ratios. Compared with the native chitosan hydrogel sample, the optimally imprinted sample (Agim75) presents a significantly enhanced Ag-I adsorption capacity as well as a high selectivity. This is attributed to the specific cavities formed by the template Ag-I ions in the polymer matrix. The effect of the adsorption conditions and desorption process were also studied.