To enhance the biocidic activity of chitosan, some known bio-cidic agents such as succinic acid, silver and palladium were tested.Succinate was introduced by treating 1 g of chitosan with 100 mLof a solution containing 10 mmol L−1succinic acid at pH 5 for 10 h.In the case of metal ions, chitosan was kept in 100 mg L−1of a pala-dium chloride or silver nitrate solution for 1 h at pH 3.5, then treatedwith a 10 g L−1sodium hyphophospyte solution (NaH2PO2·H2O) for1 h in order to reduce sorbed Ag(I) or Pd(II) to metallic Ag and Pd,respectively. Then, chitosan was rinsed with deionized water untilpH 6.5 was reached.