Catalytic activity and stability in a formic acid electro-oxidation, chemical and structural properties of AuPd nanoparticles deposited (a polyol method) on ZrO2 decorated functionalised multiwall carbon nanotubes (f-MWCNTs) (a hydrothermal method) were investigated using a fuel cell test, scanning transmission electron microscopy (STEM), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Non-stoichiometric ZrOx nanoparticles of a cubic phase (C-phase) and average size of 5-10 nm (STEM, HR-TEM), 4.5-5.0 nm (XRD) are anchored by f-MWCNTs carboxylic group through Zr-O-C bonds. Decoration by AuPd nanoparticles leads to ternary Pd/AuPd/Au phase of 6.9 nm crystallite size (XRD) with metallic Pd, oxidised (PdO, PdO2) and Pd-O-Zr phases (XPS). Oxidation/reduction at 300 degrees C/200 degrees C leads to nanoparticles sintering, increasing/decreasing Pd surface coverage, oxides/oxygen groups content and ZrOx stoichiometry. Catalysts after oxidation (the largest nanoparticle size, Pd oxides content, ZrOx stoichiometry) showed the highest activity and stability. Activity of AuPd-ZrO2/f-MWCNTs catalysts is smaller than that of these catalysts without ZrO2, however, the stability is remarkably larger, i.e. AuPd-ZrO2/f-MWCNTs > Pd-ZrO2/f-MWCNTs > AuPd/f-MWCNTs > Pd/f-MWCNTs, what is attributed to electronic properties of AuPd and role of ZrOx and oxygen functional groups in COad desorption and oxidation to CO2 releasing catalyst active sites. (C) 2018 Elsevier B.V. All rights reserved.