MnO-MnCx coated carbon nanotubes (MnO/MnCx/CNTs) nanocomposites were prepared by a one-pot deposition method. The coating consisted of MnO, Mn5C2, Mn15C4 and Mn23C6 was formed on the surface of CNTs by heating a mixture of Mn particles and CNTs at 600 degrees C for 40 min under vacuum, Then after heated MnO/MnCx/CNTs in air at 350 degrees C for 2 h, MnO nanoparticles were partially converted to Mn3O4 nanosheets. Then Mn3O4-MnCx coated carbon nanotubes (Mn3O4/MnCx/CNTs) composed of interconnected nanosheets structure were successfully synthesized by a two-step method of one-pot deposition and heat posttreatment. The Mn3O4/MnCx/CNTs showed better oxygen reduction reaction performance in alkaline condition than MnO/MnCx/CNTs and pristine CNTs. Besides, the formed MnCx (Mn5C2 and Mn23C6) by one-pot deposition method provided a strong interface bonding between Mn3O4 and CNTs, leading to improved stability of Mn3O4/MnCx/CNTs as an electrode material. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.