This paper concerns the formation of a biocompatible electrostatic complex; a conductimetric method is proposed to control the complex formation. The dissociation of chitosan in acidic medium is considered and the method for determination of the degree of acetylation is revisited. The degree of association of the complex is determined and the role of the auto-dissociation of the chitosan hydrochloride on the formation of the complex is discussed. The complex formed is very stable and cooperative for low degree of acetylation of the chitosan. The stability of the complexes formed is tested as a function of the pH. The role of the different parameters involved are examined (degree of acetylation of chitosan, external salt concentrations).