Interaction of hydrogen with sulfated zirconia catalysts was studied in situ at 473 K. Interaction of hydrogen with the sample evacuated at 673 K leads to the formation of new hydroxyl groups (wide bands near 3330 cm(-1)) and water (1620 cm(-1)). In the case of the sample evacuated at 873 K, SOH groups (3660 cm(-1)) and zirconium hydrides (1555 cm(-1)) form. Adsorption of n-pentane on sulfated zirconia catalysts in the range of 253-383 K was studied. It was shown that hydrides and protonated cyclopentadienes form at low temperatures. At higher temperatures, aromatic compounds are formed mainly. The reaction mechanism is discussed.