Initiation of the radical cation polymerization of propene has been observed following the selective ionization of benzene in the pas phase by resonance two-photon ionizatisn-high-pressure mass spectrometry (R2P1-HPMS) and by selected ion now tube (SIFT) techniques. In this system, the aromatic initiator (C6H6) has an ionization potential (LP) between those of the reactant's monomer (C3H6) curd its covalent dimer (C6H12), i.e, IP(C3H6) > IP(C6H6) > IP(C6H12) Therefore, direct charge transfer from C6H6.+ to C3H6 is not observed due to the large endothermicity of 0.48 eV, and only the adduct C6H6.+(C3H6) is formed. However, coupled reactions of charge transfer with covalent condensation are observed according to the overall process C6H6.+ + 2C(3)H(6) --> C6H12.+ + C6H6, which results in the formation of a hexene product ion, C6H12.+. The formation of this ion can make the overall process of charge transfer and covalent condensation significantly exothermic. At higher concentrations of propene, the reaction products are the propene oligomers (C3H6)(n)(.+) + With n = 2-7 and the adduct series C6H6.+(C3H6)(n) With n less than or equal to 6. The significance of the coupled reactions is that the overall process leads exclusively to the formation of the condensation product (C3H6)(n)(.+) and avoids other competitive channels in the ion/molecule reactions of propene. Gas-phase nominal second-order rate coefficients far the overall reaction into both channels are in the range of (1-3) x 10(-12) cm(3) s(-1). The rate coefficients into both channels, especially for the formation of the C6H12.+ dimer, have large negative temperature dependencies. Consistent with the gas-phase results, the intmcluster reactions of C6H6.+ produced selectively by R2PI of mixed benzene/propene clusters also do not form the monomer ion C3H6.+ but form higher propene clusters (C3H6)(n)(.+) that contain at least the C6H12.+ hexene ion. The similarity of the reaction mechanisms in the gas phase and in preformed clusters suggests that the mechanism may also apply in the condensed phase in common aromatic solvents such as benzene and toluene.