Laccase oxidation of triclosan (TCS) led to oligomerization and ether cleavage. Ether cleavage was more prominent during electrochemical TCS oxidation. Syringaldehyde (SYD) promoted TCS ether cleavage by laccase. SYD was consumed thus not acting as a recyclable “true” laccase redox mediator. Dimethoxybenzoquinone formed from SYD contributes to SYD-laccase systems' toxicity.