A novel "MnOx/Au/Pt" ternary nanocatalyst is recommended for formic acid electro-oxidation (FAO), the principal anodic reaction in direct formic acid fuel cells (DFAFCs). The protocol employed to prepare the catalyst utilized the sequential (layer-by-layer) electrodeposition of Pt (nano-Pt), Au (nano-Au) and manganese oxide (nano-MnOx) nanoparticles onto the surface of a glassy carbon (GC) support. The nano-Au enhanced the catalytic performance by changing the surface geometry to inhibit the adsorption of poisoning CO, which is a typical intermediate in the reaction mechanism of FAO, producing a potential deterioration of the catalytic performance of DFAFCs. On the other hand, nano-MnOx could successfully mediate the mechanism of FAO by accelerating the charge transfer and imparting an enhanced catalytic stability during long continuous operation. Interestingly, with this modification of the Pt/GC electrode by nano-Au and nano-MnOx, a significant (ca. 67 times that obtained at the Pt/GC electrode) enhancement in the catalytic activity toward FAO was achieved. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.