Carboxymethyl chitosan can be obtained by direct alkylation of chitosan. The Carboxymethyl chitosan achieved can be in many types: N-carboxymethyl chitosan (N-CMCS), O-carboxymethyl chitosan (O-CMCS), N,O-carboxymethyl chitosan (N,O-CMCS) and N,N-carboxymethyl chitosan (N,N-CMCS). Different reaction conditions will result in the N vs. O selectivity and different degree of substitution (DS). Carboxymethyl chitosan possesses high viscosity, large hydrodynamic volume, film- and gel-forming capabilities together with the other useful properties, such as biocompatibility, biodegradation, biological activity and low toxicity, all of which make it an attractive option in connection with its use in foods and cosmetics.