Various catalysts were used in a systematical study of selective catechol methylation to 3-methylcatechol (I) in a fixed-bed reactor of 35-mm diam. and 16-cm length. Reaction products were analyzed by gas chromatog. with mass spectrometric detection. Alumina of high purity was a suitable catalyst after partial deactivation. The formation of polymethylated catechol was avoided over this catalyst at conversion rates of 20%. The selectivity for the unwanted byproduct 4-methylcatechol was <10%. Main reaction products were I and guaiacol which is formed preferentially at low temps. Guaiacol could be converted in a following step to I by rearrangement, thus, leading to a total 80-90% selectivity for I. [on SciFinder (R)]