A microelemental, thermal, and IR spectroscopic analysis of samples of chitosan separated from fresh-and salt-water crustaceans was performed. The viscometric and optical properties of the solutions made from them — freshly prepared and during storage — were investigated. It was found that the physicochemical characteristics of crayfish shell chitosan almost do not differ from the indexes for the industrial polymer prepared from a traditional source of raw material — crab shells. This allows considering crayfish shells as an alternative raw material resource for obtaining chitosan.