The effects of zeolite (HZSM-5 was chosen for use) modified by CeO2 (CeO2/HZSM-5) on the gas-phase elemental mercury (Hg-0) removal were investigated under simulated flue gas. The Brunauer-Emmett-Teller surface area analyses, powder X-ray diffraction measurements, and thermogravimetric analyses were employed to characterize the samples. The experimental results showed that there was a synergetic effect between CeO2 and HZSM-5 on Hg-0 removal. The acidic sites of HZSM-5 could effectively adsorb Hg-0 from the flue gas, and CeO2 could significantly enhance the oxidation of adsorbed Hg-0. However, the surface area of CeO2/HZSM-5 decreased because of excess CeO2, which was detrimental to its Hg-0 removal efficiency. Moreover, the temperature tests manifested that 6% CeO2/HZSM-5 achieved high Hg-0 removal efficiency at low reaction temperatures (<300 degrees C). Additionally, the Hg-0 removal efficiencies of CeO2/HZSM-5 were found to be significantly affected by the flue gas components. In the presence of O-2, promotional effects of NO and SO2 on the Hg-0 removal were found, while the presence of H2O inhibited the Hg-0 removal in this experiment. Furthermore, after regeneration, CeO2/HZSM-5 still possessed good reactivity and its Hg-0 removal efficiency stayed above 92% in 30 h.