Adsorption of Cu (II) ions by untreated sugarcane bagasse (USCB) and treated sugarcane bagasse (TSCB) was investigated. Sugarcane bagasse was treated with 0.1M oxalic acid prior to TSCB adsorption studies. Dependence of Cu (II) adsorption on pH, contact time, temperature and initial concentration of adsorbate solution were also investigated. Optimum pH 2 and contact time of 100 minutes were observed for both USCB and TSCB, while Cu II sorption increased with temperature. Under optimum condition, TSCB adsorbed Cu (II) ions better than USCB (1.854mgg-1and 0.556mgg-1respectively). Thermodynamic investigations showed that Cu (II) adsorption was feasible, spontaneous and endothermic. Kinetic data was adequately described by Ho’s pseudo-second-order kinetic model while intra-particle diffusion model described a slow adsorption affinity. It was concluded that Cu (II) adsorption by sugarcane bagasse is a favourable chemisorption process and was well explained by both Langmuir and Freundlich isotherms.