Alkylation of biphenyl with 1-octene was investigated using ((Al+C3H7Cl)+C2H4) catalysts. The catalytic activity of ((Al+C3H7Cl)+C2H4) for the alkylation was studied at different temperatures, mol ratios of biphenyl to 1-octene, reaction times and catalyst concentrations. It was shown that using this catalyst has more advantagous than another catalysts. Experiments show that by increasing temperature the alkylation process accelerates and the amounts of obtained octylbiphenyls increases. It is observed. that selectivity of monooctylbiphenyls increases by increasing catalyst concentration and mol ratio of biphenyl to 1-octene. Optimum conditions were determined for mono-, di- and polyoctylbiphenyls.