The objective of this study is to compare the performances of chitosan/banana peel (CS/BP) biocomposite with chitosan (CS). CS, BP and CS/BP composite biomaterials were characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermal gravimetric analyses (TGA). Their specific adsorption characteristics were assessed by using a basic dye (Methylene Blue [MB]) as a model adsorbate. The influence of various experimental factors such as contact time, initial dye concentration, pH of dye solution, ionic strength and inorganic salts was investigated. The adsorption of MB from aqueous solutions was investigated using a CS/BP biocomposite and CS as adsorbents. The materials are capable of removing color from wastewater, their color removal capacity for CS is 81% and CS/banana peel biocomposite is 96% at normal pH and temperature conditions. The equilibrium times founded correspond to 150 min for CS and 100 min for CS/banana peel biocomposite. The kinetics of adsorption suggested a pseudo-second-order model fits better than pseudo-first-order model and the equilibrium isotherm fitted the Langmuir and Freundlich models. The results of this study will be useful for future scale-up using this composite biomaterial as a low-cost adsorbent for the removal of cationic dyes.