Absorption of isobutylene in p-cresol to prepare butylated hydroxytoluene (BHT), an important antioxidant, has been studied by using solid sulfated zirconia. Absorption is accompanied by complex chemical reactions. Detailed theoretical and experimental analysis of this system is reported here, and kinetic parameters have been established. Effects of various parameters such as partial pressure of isobutylene, catalyst loading, particle size, and temperature on the rates of reaction have been analyzed.