Biocatalytic oxidative processes wherein oxidizable substrates are reacted in the presence of soybean peroxidase are described. Preferred biocatalytic oxidative reactions include the oxidation of sulfides, O-dealkylation of alkyl aryl ethers, N-dealkylation of aromatic amines, halogenation of halogen-reactive compounds and polymerization of aromatic amines. Examples of such reactions include the oxidation of alkyl aryl sulfides, the O-dealkylation of methoxybenzenes, the N-dealkylation of N,N-dimethyl aromatic amines halogenation of 5,5-dimethyl 1,3-cyclohexane dione, and the polymerization of aniline which can yield an intrinsically conductive polymer (ICP). A solution of substrate is prepared and then contacted with soybean peroxidasein the presence of a peroxide, preferably hydrogen peroxide. The reactions are preferably carried out in the presence of 10 to 100 mM calcium ions.