An electrochemical biosensor for remote continuous monitoring of phenolic compounds in environmental analysis is described. The probe relies on rapid and sensitive amperometric detection at a submersible biosensor assembly, connected to a 50 ft long shielded cable. The enzymes laccase and tyrosinase were used as individual sensors and also as a bienzymatic sensor; these enzymes were immobilized chemically on the carbon fiber transducer. The analysis was based on the amperometric detection of the enzymatic products at a potential of â 0.10 V vs. Ag/AgCl. Operational conditions were optimized to meet the requirements of remote operations. Tests with untreated river water spiked with phenolic compounds gave results similar to those obtained with synthetic buffer solutions. The remote laccase biosensor allowed the convenient quantification of guaiacol and chloroguaiacol at levels down to 22 and 9 nmol L^{â 1}, respectively. The co-immobilization of laccase and tyrosinase allowed the efficient detection of a larger group of phenolic compounds.