The reaction mechanism for oxygen reduction reaction (ORR) on Si-doped divacancy graphene is investigated by employing the density functional method. Our results show that all of the possible ORR elementary steps and charge transfer could take place within a small active region around the Si atom and its adjacent four carbon atoms. Among the possible reaction pathways, O-2 dissociation and OOH hydrogenation into O + H2O are the most favorable pathways kinetically. The rate-determining step is the O atom hydrogenation into OH with an energy barrier of 1.13 eV. This value is similar to 1.11 eV for the single layer SiC and 1.18 eV for SiC2. Si-doped divacancy graphene has good tolerance against CO poisoning compared with Pt (111). Thus, Si-doped divacancy graphene could be a promising metal-free catalyst for ORR. (C) 2016 The Electrochemical Society. All rights reserved.