To enhance the co-benefits of elemental mercury (Hg-0) oxidation across the selective catalytic reduction (NH3-SCR) units and to minimize slip ammonia (unreacted reductant) from flue gases, the conception of SCR-Plus was put forwarded and the catalysts were investigated. The SCR-Plus catalysts were prepared by modifying the conventional SCR catalyst with molybdenum (Mo) and ruthenium (Ru) to meet such purposes at relatively high space velocity. It was found the doping of Mo to Ru/SCR catalyst could significantly reduce the demand content of Ru, and the catalyst exhibited outstanding catalytic activity for Hg-0 oxidation and more tolerant to the inhibition of SO2 and ammonia, respectively. Meanwhile, the cooperation of Mo and Ru in the SCR catalyst facilitated the abatement of slip ammonia. The Hg-0 removal efficiency of the Mo/Ru-SCR catalyst was greater than 99% when approximately 5 ppm of HCl was added to the simulated flue gas. Meanwhile, Deacon reaction evaluation and in situ diffuse reflectance infrared Fourier transform (DRIFT) technique were performed for the possible reaction mechanisms. (C) 2014 Elsevier Ltd. All rights reserved.