A simple and eco-friendly process for the isomerization of carvone to carvacrol in the presence of SO(4)(2-)/ZrO(2) catalyst has been described. The reaction is conducted without solvent at moderate temperature with reaction times of 1 to 2 h. In most instances, nearly quantitative yield of carvacrol is obtained without any by-products. The total acidity, different acid concentration, zircona phases and crystallites size were co-related with the catalytic activity. Activation energy is found to be 11.317 kJ/mol using 8% SO(4)(2-) ions modified zircona. The bulk and surface properties of the prepared catalysts are examined by X-ray powder diffraction, BET surface area and ammonia-TPD.