Noncatalytic and catalytic pyrolysis of toluene has been studied at atmospheric pressure in :he temperature range of 1043 to 1153 K using steam or nitrogen as the diluent. The catalyst used was potassium carbonate impregnated calcium aluminate. Compared to noncatalytic pyrolysis, the conversions were significantly higher in the presence of the catalyst although the product selectivities were not affected. With nitrogen as the diluent the main products were hydrogen, methane, benzene, bibenzyl and higher hydrocarbons. When steam was used as the diluent, in addition to the above products appreciable amounts of carbon monoxide and carbon dioxide were also produced. The overall reaction of toluene could be represented by two parallel paths; one for toluene decomposition and the other for the toluene-steam reaction. The kinetic constants of these two reactions for catalytic as well as noncatalytic pyrolysis were determined by nonlinear optimization. In the presence of the catalyst, the activation energy for toluene decompostion was significantly reduced, whereas there was only a marginal reduction in the activation energy of the toluene-steam reaction.