Selective dimerization of styrene to 1,3-diphenylbutene-1 in the presence of [(acac)Pd(PAr3)(2)]BF4 + BF3OEt2 catalytic systems, where R = C6H5, o-CH3C6H4, p-CH3C6H4, or o-CH3OC6H4, has been studied. Under the optimal conditions (B/Pd = 8, T = 75 C, R = C6H5), the conversion of styrene to the products exceeds the conversion for the known analogs and reaches 1.5 tons of styrene/g-atom of palladium with amounts of dimers and trimers of 91 and 9%, respectively. The dimers consist of up to 100% 1,3-diphenylbutene-1 with a trans/cis isomer ratio of 95/5.