Various rhodium complexes were examined for oxidative arylation of ethylene with benzene to directly produce styrene. Using Rh(ppy)(2)(OAc) (1) (ppyH = 2-phenylpyridine), the reaction of benzene with ethylene gives styrene and vinyl acetate in 77 and 23% selectivities, respectively, in contrast to the selectivities using Pd(OAc)(2), which are 47% styrene and 53% vinyl acetate. The observation that complex 1 is an active catalyst for both styrene formation and H-D exchange between CH3CO2D and C6H6 suggests that styrene formation involves a Rh-mediated, benzene CH bond activation process. The crystal structures of complex 1 and Rh(PPY)(2) (acac-O,O') (2) (acac = acetylacetonato) are also reported. Rh(acac)(CO)(2) also works as catalyst for styrene formation by addition of acacH and O-2 without any oxidizing agent, such as Cu salt. In this system, vinyl acetate is not formed at all in spite of the presence of acetic acid.