Commercial and extracted mushroom tyrosinases were supported on Eupergit C 250 L and protected by a coating of oppositely charged polyelectrolytes by means of the layer-by-layer technique. The kinetic parameters (Km, Vmax, and Vmax/Km) of these novel biocatalysts in both organic and aqueous media were evaluated, showing tyrosinase to be more reactive in organic solvent than in buffer solution. Heterogeneous tyrosinase systems were used for the oxidation of a large group of phenol derivatives to the corresponding catechols. Different enzyme reactivities were found depending on the substrate structure. The catalyst activity was retained for successive runs. Catechols are difficult to synthesize through traditional chemical methods under environmentally friendly conditions; the use of immobilized tyrosinase opens a novel synthetic alternative to this interesting biologically active family of substances.