This study addresses formic acid (FA) electro-oxidation (FAO) at a binary catalyst composed of palladium (PdNPs) and nickel oxide (nano-NiOx) nanoparticles electrodeposited onto a glassy carbon (GC) electrode. The deposition sequence of PdNPs and nano-NiOx onto the GC electrode is properly adjusted in such a way that maximizes the electrode efficiency toward FAO. The highest catalytic activity and stability are obtained at the NiOx/Pd/GC electrode (with PdNPs directly deposited onto the GC electrode followed with nano-NiOx with an optimum surface coverage, Gamma, of ca. 41%). The enhancement is manifested in the increase of the oxidation peak current of FA together with a favorable negative shift of the onset potential of FAO. It is believed that nano-NiOx could facilitate the direct oxidation of FA via minimizing the amount of the poisoning species at the Pd surface. (c) 2015 The Electrochemical Society. All rights reserved.