Enzymatic oxidative polymerization of 2,6-dimethylphenol has been carried out in an aqueous organic solvent at room temperature under air. Laccase derived from Pycnoporus coccineous and horseradish and soybean peroxidases were active for the polymerization, yielding polymeric materials with molecular weights of several thousands. The product polymer was in all cases soluble in common organic solvents. The polymerization behavior was dependent on the enzyme type. The effects of the solvent composition have been systematically investigated with respect to the polymer yield and molecular weight. The mixing ratio between the organic solvent and buffer affected the polymer yield, and the highest yield was achieved in 60% buffer. Various water-miscible organic solvents such as acetone, methanol, and 1,4-dioxane were available as components of the mixed solvent. In using laccase catalyst, the acidic buffer afforded the polymer in high yields. NMR and matrix-assisted laser desorption/ionization time of flight mass spectroscopic analyses showed that the present polymer was exclusively composed of 2,6-dimethyl-1,4-oxyphenylene units.