The reactions of styrene with benzene to activate the aromatic C-H bond have been carried out using Pd(NO₃)₂ and phosphines (PR₃, R=C_6H_5, p-C_6H₄CH₃, p-C_6H₄F, C_6H_(11)) as the catalytic system. The reaction conditions in this work (55 ℃, 20 psi O₂, 20 h) has been kept identical to those in the previously reported work using Pd(OAc)₂ and phosphines to compare the effect of nitrate with acetate. The yield of the product, trans-stilbene, increases as the electron donating ability of the substituents on the phosphine increases and decreases as the steric hindrance increases; P(C_6H_5)₃ > P(C_6H_(11))₃ > P(p-C_6H₄CH₃)₃ >> P(p-C_6H₄F)₃. On the other hand, the migratory aptitude of the substituent in phosphine to the palladium metal is reinforced as the electronegativity of the substituent increases. Generally, the yield of the product is lower for the less basic nitrate system than for the acetate one, which shows a parallel result with the above substituent effect.