The influence of various reaction parameters such as temperature, WHSV, time on stream, and feed ratio of benzene to 2-propanol, as well as of the Si/Al molar ratio of zeolite NCL-1, on catalytic activity and selectivity was studied in the isopropylation of benzene with 2-propanol. The selectivity towards cumene increases with Al content, contact time, and ratio of benzene to 2-propanol. Among diisopropylbenzenes (DIPBS), the concentration of 1,3-DIPB (vis-g-vis 1,4-DIPB) increases with increases in reaction temperature, Al content of the catalyst, and benzene conversion. The 1,2-DIPB, with relatively high strain energy (4.26 kcal mol(-1)) compared to that of either 1,3-DIPB (2.02 kcal mol(-1)) or 1,4-DIPB (2.78 kcal mol(-1)), was formed in very small quantities (0-2 wt%).