Cracking of cyclohexane has been performed over a HZSM-5 catalyst with Si/Al ratios 28, 85 and 200, in the temperature region 400-650 degrees C and with partial pressures of cyclohexane up to 2 bar. The cracking kinetics for Si/Al = 200 can be adequately modelled by simple first order kinetics. Olefins and benzene appear to be the primary products from the cracking reaction, while alkanes and higher aromatics behave as secondary products. Combined selectivities of ethene + propene increase with increasing temperature, and more than 60% selectivity can be reached. Under the reaction conditions very rapid equilibration of olefins heavier than ethene is obtained. The addition of hydrogen to the cracking feed has only a small influence on the rate of formation of saturated compounds. (C) 2010 Elsevier B.V. All rights reserved.