This study covered the preparation and characterization of durian husk cellulose (DHC)-filled chitosan (CS) biocomposite films. The effects of the DHC content and bleaching treatment via hydrogen peroxide (H 2 O 2 ) on the tensile and thermal properties of the CS/DHC biocomposite films were investigated. The results showed that the tensile strength and percentage of elongation at break decreased with increasing DHC contents, but the modulus of elasticity of the CS/DHC biocomposite films increased along with the DHC contents. The bleaching treatment of the durian husk is to remove the lignin content to form bleached DHC, resulting in an improvement of tensile strength, modulus of elasticity, and thermal properties of bleached CS/DHC biocomposite films. The functional groups of the unbleached and bleached DHC filler were proved by the Fourier transform infrared (FTIR) analysis, and the thermal stability and glass transition temperature (T g ) of the CS/DHC biocomposite films were measured by the thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) analysis, respectively. K E Y W O R D S bleaching treatment, chitosan, durian husk cellulose, films, hydrogen peroxide