Novel catalytic systems for the cationic oligomerization of 1-decene into synthetic poly(α-olefin) oils have been worked out; these systems include a highly disperse (0.1–40 μm) aluminum, an aluminum activator [I2, Mg, (C2H5)nAlCl3 − n, (CH3)3CCl and some other RX, HCl, benzene, and toluene], and a cocatalyst based on organic halide compounds RX (R is primary, secondary, or tertiary alkyl, allyl, or benzyl; X is Cl, Br, or I). We study the effect of various factors (characteristics of Al, nature of aluminum activator, RCl: Al molar ratio in the catalyst, concentration of Al, temperature, benzene additives, reaction duration) on the conversion of 1-decene into poly(α-olefins), the fractional composition of oligomerization products, the content of chlorine in poly(α-olefins), and the structure and physicochemical characteristics of fractions.