Effect of Pt particle size on the catalytic activity of complete ethylene oxidation in the temperature range of 25-220 degrees C in fuel-lean conditions is investigated. Carbon black is used as a support for platinum nanoparticles of well-defined average sizes between 1.5 and 6.3 nm. The results demonstrate that ethylene oxidation on Pt/C is strongly size sensitive reaction. Thus, the smallest Pt/C-4 nanoparticles (1.5 +/- 0.5 nm) exhibit much higher catalytic activity toward ethylene oxidation reaching 50% conversion at 88 degrees C compared to 164 degrees C for the largest Pt/C-1 (6.3 +/- 0.5 nm) nanocatalysts. XPS shows that particle size decrease results in noticeable binding energy increase and Pt4f peak broadenings. This indicates that the electronic effect induced by small Pt nanoparticles might play a role in the observed increase in their activity toward C2H4 oxidation. (C) 2013 Elsevier B.V. All rights reserved.