Transformation of 2-tert-butylphenol (2TBP) in heterogeneous solid-liquid catalytic systems has been investigated. To reach the desired temperature, reaction mixtures were heated up by conventional (CH) and microwaves (MW) methods. Solid catalysts of different acidity (zeolite HZSM5 and Mordenite, Montmorillonite KSF and K10, neutral, weakly acid and acidic alumina, Bentonite), polar and non-polar solvents, as well as the activation of the catalyst and the modality of introducing the microwave energy into the reaction mixture have been studied. Results were discussed in terms of reaction pathway, selectivity and reaction rate indicating superheating effect of catalyst. The observed unusual dilution effect resulting surprisingly in higher reaction rate was explained by a catalytic mechanism. (C) 2002 Elsevier Science B.V. All rights reserved.