Rates of C-3-C-5 ketone hydrogenation are measured in the vapor phase over Ru/SiO2. Reaction kinetics are considered through a range of ketone partial pressures (0.3-30 Torr), hydrogen partial pressures (90900 Torr), and reaction temperatures (322-456 K). Ketone hydrogenation is observed to be facile, with site time yields ranging from 0.14 s(-1) for 2-pentanone to 0.37 s(-1) for acetone at 322 K and 1.2 bar H-2. At low temperatures, apparent reaction orders and kinetic barriers are similar for all ketones. During acetone hydrogenation at higher temperatures, (422 K), the ketone order increases from 0 to 0.4, while the hydrogen order increases from 0.5 to 0.9. Furthermore, the apparent barrier decreases from approximate to 50 kJ mot(-1) at 322 K to approximate to 18 kJ mol(-1). Apparent trends in hydrogenation rates are interpreted at an elementary level using a microkinetic analysis that is based on a Horiuti-Polanyi mechanism involving two distinct surface sites. (C) 2017 Elsevier Inc. All rights reserved.