The acid-catalyzed hydroxymethylation of 2-methoxyphenol (guaiacol) with formaldehyde aimed at the synthesis of benzyl alcohol derivatives (vanillic alcohols) was studied with specific attention being given to the role of methanol which is present in commercial aqueous solutions of formaldehyde. Methanol had a pronounced effect on the catalytic performance with both homogeneous and heterogeneous acid catalysts. Specifically, the conversion of guaiacol decreased considerably with increasing amounts of methanol in the formaldehyde solution, and the distribution of products is also changed. In the absence of methanol the formation of diaryl compounds predominated over the formation of monoaryl by-products. (C) 2002 Elsevier Science B.V. All rights reserved.