An electrochemical catalyst based on Au nanoparticles dispersed in an yttria-stabilized zirconia (YSZ) matrix was prepared by reactive cosputtering of zirconium-yttrium and Au targets on a K-beta Al2O3 solid electrolyte. The Au/YSZ catalyst film deposited on K-beta Al2O3 was found to be active in the partial oxidation of methanol with a high selectivity toward methyl formate. This configuration allowed to electrochemically promote a highly dispersed Au catalyst by K+ ions and allowed to decrease the amount of metal used in the solid electrolyte cell. The back-spillover of K+ ions sharply increased the H-2 and HCOOCH3 production rates up to more than 9 and 5 times, respectively. A number of experiments confirmed that the observed electro-promotional effect did not depend on the rate of K+ supply nor on the operation mode (galvanostatic or potentiostatic) and only depended on the promoter coverage (total applied charge). The stability of the Au-YSZ catalyst film under the explored conditions was also verified. (c) 2014 Elsevier Inc. All rights reserved.