An outer combined plasma photolysis (OCPP) reactor that simultaneously utilized a dielectric barrier discharge (DBD) plasma and UV radiation from DBD-driven KrI* excimer was designed and constructed. Gas streams containing benzene were treated with normal DBD and OCPP at atmospheric pressure. In contrast to DBD, benzene removal efficiency increased by 15.9% in OCPP when applied voltage, gas flow rate and initial concentration of benzene were set at 9 kV, 35 L min−1 and 800 mg m−3, respectively. Thus, the applied voltage could be reduced to a certain extent in the plasma decomposition of pollutants with OCPP. In addition, the effects of various operational parameters including pressure of filled Kr, ratio of Kr/I2 and quartz dielectric characteristics on OCPP performance were investigated. Finally, the likely reaction mechanisms for the removal of benzene by OCPP were suggested on the basis of the emission spectra of KrI* excimer and byproducts analysis. Those results would offer prospective commercial applications for pollutant decomposition with OCPP.