The aim of this work was to prepare the metal oxides modified carbon (C-MOx) that was used as the support for a PtCo catalyst. Effect of C-MOx support on the oxygen reduction reaction activity and stability of the PtCo catalysts in acid electrolyte and in proton exchange membrane fuel cell was explored at ambient pressure. It was found that the use of respective C-MOx support changed the morphologies (degree of alloying and particle sizes) as well as the electrochemical properties (electrode resistance and electrochemical surface area) of the obtained PtCo catalyst. In addition, it enhanced the formation of Pt atoms with a small d-electron occupancy, which consequently affected positively the ORR activity of the PtCo catalysts. Among the three utilized C-MOx support (C-TiOx, C-CeOx, C-MoOx), the C-MoOx exhibited the highest ORR activity in an acid electrolyte monitored in terms of kinetic current density and the highest current density of 570 mA/cm(2) at 60 degrees C and 1 atm (abs) in a proton exchange membrane (PEM) fuel cell. In addition, it also achieved a comparable stability of PtCo catalyst to that of C-TiOx support, which were higher than that of the commercial carbon support. (C) 2019 Elsevier Ltd. All rights reserved.