An Ag-8 cluster deposited on three different types of nitrogen (N)-doped graphene was studied using density functional theory calculations with empirical pair potentials (DFT-D). Among the different kinds of N-doped graphene, the pyridinic-N-3 (P-N-3) type can act as the best anchor position to stabilize Ag-8. In addition, it is found that supported Ag-8 clusters show higher activity in oxygen reduction reaction compared to unsupported clusters due to significant decrease in O-2 adsorption energy and higher charge transfer to O-2. Electron transfer from Ag to O-2 leads to the elongation of the O-O bond, which facilitates the breaking of this bond in the oxygen reduction reaction. All results suggest that N-doped graphene support can play a significant role in the chemical reactivity of a Ag-8 cluster in oxygen reduction reaction. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.