A biocomposite system was developed and tested for the removal of the azo dye Reative Red (RR195) from wastewater. The biocomposite was synthesized using ceramic particles containing 75% alumina which were coated using chitosan crosslinked with oxalic acid. The biocomposite showed high performance at low pH (maximum adsorption capacity = 345.3mg.g− 1 at pH = 2). The physico-chemical and structure characteristics of the matrix were evaluated by Z-potential, FTIR-ATR, SEM-EDS, DRX and porosity. Langmuir sorption isotherm and Pseudo Second order model gave the best fit. The electrostatic interaction between RR195 (due to the sulfonate groups) and the free amino groups of chitosan, enabled successive desorption/regeneration cycles. The maximum removal percentage (> 80%) occurred at pH = 2 due to the crosslinking effect. Experiments at different temperatures allowed the calculation of thermodynamic parameters (ΔG, ΔS, ΔH); adsorption was spontaneous, exothermic and enthalpy controlled. The presence of inorganic ions (NO3−>Cl−) was analyzed during the adsorption process. This novel biocomposite can be applied as a cost-effective and environmentally friendly adsorbent for anionic azo dye removal from wastewater. The application of chitosan crosslinked with oxalic acid as a coating of the ceramic support enhanced the adsorption capacity and enabled its use under acidic conditions without solubilization.