This study is mainly concerned with the characterization of an immobilized laccase from the white-rot fungus Lentinula edodes for use in wastewater treatment. The enzyme was immobilized on chitosan by adsorption and subsequent cross-linking with glutaraldehyde. The immobilized laccase displayed a lower specific activity and a lower substrate affinity than the free enzyme. Nevertheless, the immobilized catalyst exhibited an appreciable catalytic capability (520 units g(-1) support) along with remarkably improved stability properties to various parameters, such as temperature, pH and storage time. The treatment of olive mill wastewater with immobilized laccase led to a partial decolorization as well as to significant abatements in its content in polyphenols, ortho-diphenols combined with a decreased toxicity of the effluent.