The aromatic polymer lignin is the second most abundant polymer found on Earth. Found naturally in terrestrial plants, lignin is a common waste product of the paper and biofuel industries. The biological valorisation of lignin has the potential to supply useful chemicals and materials traditionally derived from non-renewable feedstocks. However, a roadblock limiting efficient microbial valorisation of lignin is the availability of enzymes that catalyse the rate limiting O-demethylation of lignin derived aromatic compounds (LDACs). We have biochemically and structurally characterised a bacterial Cytochrome P450 from Amycolatopsis thermoflava N1165 (SyoA) that catalyses the O-demethylation of the underutilised LDAC syringol. We demonstrate that SyoA and the guaiacol O-demethylase GcoA are peroxygenases that can use H2O2 to catalyse the O-demethylation of their substrates. The high-resolution structure (1.3 Å) of SyoA reveals structural differences that are critical in distinguishing between guaiacol and syringol based O-demethylases and the mechanisms involving peroxygenase activity. This work expands the toolkit for the enzymatic bioconversion of S-type lignin and allows for a cheap and clean method for the O-demethylation of aromatics compared to nicotinamide cofactor-dependent monooxygenase systems.