1. Benzene has been alkylated with isobutylene using sulfuric acid of various concentrations, and some of the results of V. N. Ipatieff, B. B. Corson and H. Pines have been reconfirmed. The alkylation takes place predominantly with 91–96% sulfuric acid. 2. Using 91% sulfuric acid as catalyst, benzene has been alkylated with varied amount of isobutylene against benzene. The increase of the yield of tert-butyl benzene caused by the decrease of the amount of isobutylene against benzene is not remarkable, forming a considerable amount of p-di-tert-butyl benzene fraction. By the increase of the amount of isobutylene against benzene, the yield of p-di-tert-butyl benzene fraction increases to the main reaction product, with the decrease of tert-butyl benzene fraction. The reaction of excess isobutylene with benzene causes the mere polymerisation of isobutylene with 91% sulfuric acid to yield high-boiling olefinic polymer after complete alkylation of benzene. 3. tert-Butyl benzene and p-di-tert-butyl benzene have been readily hydrogenated into tert-butyl cyclohexane and 1,4-di-tert-butyl cyclohexane, respectively, using nickel-kieselguhr catalyst. 1,4-Di-tert-butyl cyclohexane is a mixture of cis and trans isomers, and is partially crystal？ised at room temperature and melts completely at 31°C. 4. Octane numbers. of 1,4-di-tert-butyl cyclohexane, tert-butyl cyclohexane and the high boiling aromatic hydrocarbon CF2R have been measured. 1,4-Di-tert-butyl cyclohexane has high octane numbers as predicted, the 20% blending octane number amounting to 113. It has the flash point of 80.5°C., and is highly soluble in hydrocarbones, and there？ore may be used as a constituent of safety fuels.