The subject of our studies was determination of the kind and strength of the catalyst acid centres on isopropyl alcohol conversion. The investigations were carried out for two groups of catalysts: typical Lewis acids gamma-Al2O3 and ZrO2 and Bronsted acids: H3PW12O40 and H3PMo12O40. Considerable differences between Lewis and Bronsted acids in the conversion of isopropyl alcohol were observed. The influence of Bronsted acid centres was studied for a group of catalysts with different strength: mixtures of two different heteropolyacids. It was observed that the increasing strength of Bronsted acids centres leads to higher catalytic activity but it does not significantly affect the activation energy of dehydration to propene. (c) 2005 Published by Elsevier B.V.