Three structurally different aniline monomers, which can not be polymerized by chemical methods, have been polymerized with horseradish peroxidase. Enzymatic synthesis of linear polyaniline requires template molecules to minimize branching in the polyaniline backbone. Monomers having methoxy and methyl blocking groups at the ortho or meta position could induce the conducting form of para-linked polyaniline without the use of an anionic template, such as SPS. A new mild peroxide, peroxyacetic acid, was identified and used to oxidize horseradish peroxidase in water.