The main aspects of aluminum chloride-catalyzed cooligomerization of 2-ethylbutene-1 with butene-1, hexene-1, isobutene, and olefins of industrial fraction were studied. The formation of cooligomers of 2-ethylbutene-1 with these olefins was proved using spectral techniques. The influence of the initial 2-ethylbutene-1 : olefin mole ratio on the monomer yield at different temperatures and catalyst quantities was examined. Possible cooligomerization mechanisms were suggested.