Plasma reduction of graphene oxide is a promising route towards large-scale and low-cost graphene production. Here we demonstrate a facile, heating-free approach of fast reduction of graphene oxide using inductively coupled methane/argon plasma. The reduction mechanism involves two coexisting and competing processes, which eventually determines the reduction efficiency. The defect restoration and etching-free effect of methane-based plasma produces reduced graphene oxide with performances superior to those achieved by room-temperature hydrogen plasma reduction. With the optimization of gas ratio and treatment time, the C/O ratio increased from 2.2 to 10.6 with an enhanced conductivity of 264.5 S/m. This approach paves the way towards fast, room-temperature and eco-friendly production of reduced graphene oxide for the applications of flexible electronics. (C) 2018 Elsevier B.V. All rights reserved.