In the cracking of gas oil, silica-alumina was extensively used as a carrier agent. Metal or metal-oxide impregnation into its matrix increases the activity of the catalyst. As an improvement over the studies made on the efficacy of doped silica-alumina systems in cracking reactions, oxides of magnesium, boron, titanium, zirconium, chromium and molybdenum were incorporated in the matrix of silica-alumina catalyst. The cracking efficiency of the prepared catalysts was ascertained by using them in model reactions involving alkyl benzenes. The gas oil was cracked at four different temperatures between 450 and 600 degrees C at a contact time of 0.0997 h employing the prepared catalysts. The products of the above cracking reactions were separated into gas, gasoline and middle distillate and estimated. The maximum yield of gasoline was between 53 and 58 % and the maximum octane number was found to be 93. The product distribution is suggestive of a carbonium ion mechanism being involved.