The newly developed Sm0.95Ce0.05Fe1-xCoxO3-delta perovskites were assessed as sensors for reducing gases. The solid state sensors were prepared in the form of pellets. Sensors with larger particle size and reduced grain boundaries are obtained as the concentration of cobalt is increased. The sensor's surface is enriched with Sm and Co, but the Sm concentration decreases with an increase in cobalt content. The introduction of cobalt in the perovskite lattice results in an increase in lattice oxygen and a decrease in surface adsorbed oxygen. The electrical conductivity responses toward H-2, CO and CH4 (1-5% v/v) were measured in air and at different temperatures. The cobalt doping has improved the response to such an extent that H-2, CO and CH4 can be detected at room temperature. Response and recovery time of these sensors are associated with surface chemical composition and surface morphology. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3570674] All rights reserved.