This work describes the application of the N-demethylase activity of immobilized soybean lipoxygenase to the oxidative degradation of xenobiotics. Previously (1) we have shown that immobilized lipoxygenase produces the oxidative degradation of CPZ in the presence of hydrogen peroxide. As a continuation of this work, here we studied the N-demethylation of CPZ by the hydroperoxidase activity of covalent immobilized soybean lipoxygenase. The obtained results clearly reveal that the immobilized system produces the N-demethylation of CPZ in the presence of hydrogen peroxide, maintaining a high level of activity in comparison with free enzyme. Additionally, the immobilized lipoxygenase shows stability higher than that of free enzyme, making feasible its use in a bioreactor operating in continuous or discontinuous mode. The results obtained in this work, together with those obtained previously by us for the oxidation of CPZ, suggest that hydroperoxidase activity of immobilized lipoxygenase may constitute a valuable tool for oxidative xenobiotics degradation or for application to synthetic processes in which a N-demethylation reaction is involved.