Chemical modification of chitosan becomes a promising strategic to improve its physicochemical and biological properties which potentially applied in biomedical application. This work aimed to evaluate the effect of several radical initiator types on antioxidant and antibacterial activities of chitosan-ferulic acid conjugates. The conjugation reaction system used formic acid/H2O2, t-butanol/H2O2, oxalic acid/H2O2, ascorbic acid/H2O2, citric acid/H2O2, and malonic acid/H2O2 as redox pairs. The physicochemical properties of conjugate products were studied based on the total phenolic content, morphology image, thermal behavior, and infra red analyses. All conjugate products showed the improvement of the antioxidant activities. Furthermore, conjugation reaction employing many types of radical initiator system enhanced the total phenolic content of chitosan. [ABSTRACT FROM AUTHOR]