Methanol production resulting from the demethoxylation of lignin‐related substances by Phanerochaete chrysosporium K‐3 was studied in the presence or absence of glutamic acid in order to determine if methanol formation involved the ligninolytic system of the fungus. The general pattern was that methanol formation, calculated as percentage of theoretical yield, decreased in the order guaiacyl > syringyl > veratryl (3,4‐dimethoxy) compounds. Methoxyhydroquinone and vanillic acid were most easily demethoxylated, while methanol production decreased with increasing molecular weight for the same type of structure (i.e. guaiacyl). Glutamic acid inhibited the demethoxylation of many of the compounds tested. The demethoxylation of the 4‐methoxy group of veratric acid was particularly inhibited by glutamic acid suggesting a participation of the ligninolytic system, while the 3‐methoxy group was influenced to a lesser extent.The demethoxylating enzyme acting on lignin‐related phenols is probably a peroxidase, while the identity of the enzyme demethoxylating dimethoxy compounds is not known with certainty, although a peroxidase type of enzyme reaction is anticipated also here.