CO electrooxidation on nanocrystalline molybdenum carbide has been studied through CO stripping measurements using cyclic voltammetry. The active molybdenum carbide was obtained from the carbothermic reduction of really very small molybdenum oxide particles supported on Vulcan XC-72 carbon black (CB). In order to obtain highly dispersed molybdenum carbide particles, low molybdenum loading and control of the carbothermic reduction conditions of CB-supported molybdenum oxide were employed to avoid Mo sintering during the carburization process. This work provides experimental evidence on the CO electrooxidation capability of the Mo carbide phase, which to the best of our knowledge is reported for the first time. The small particle size of carbide electrocatalyst exhibited better performance for CO electrooxidation than the commercial bulk molybdenum carbide sample. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.