BACKGROUND: Triclosan is a biocide used in personal care products, and its presence in water bodies has been reported. This compound is suspected to be linked with the emergence of antibiotic-resistant bacteria. In the present work, the enzyme horseradish peroxidase (HRP) was used to catalyze triclosan removal. RESULTS: The stoichiometric ratio of H2O2 to triclosan (0.83) was higher than the value predicted by the HRP catalytic cycle (0.5). During the reactions, HRP activity was gradually reduced, likely due to excess H2O2. The addition of veratryl alcohol, syringaldazine and p-coumaric acid (redox mediators) to the reaction medium, at a mediator/triclosan molar ratio of 1.0, increased triclosan removal from 45% (without a mediator) to 56%, 64% and 80%, respectively. The antibacterial activity of these mediators was much lower than that observed for triclosan. CONCLUSION: The antibacterial activity of triclosan solution was effectively reduced after enzymatic treatment. Moreover, the enzymatic process was proven to be technically feasible for removing triclosan at an environmental relevant concentration. (c) 2012 Society of Chemical Industry