A rapid procedure for determining phenols in olive oils, based on an organic-phase enzyme electrode, is described. Direct assays are performed in chloroform solutions which support the tyrosinase activity. This class (phenol)-specific enzyme strongly adheres to the surface of the graphite transducer. The resulting wall-jet detector offers effective flow injection operation, with a detection limit of 4×10⁻⁷ M (0.8 ng) phenol and sample frequency of 60 h⁻¹. Applicability to olive-oil samples of different origins is illustrated.