This study describes the design and operation of a 100 kW chemical-looping combustor for solid fuels. Six experiments of continuous operation, varying between 8 and 32 min in length, have been conducted. The fuels investigated were a Mexican petroleum coke and a bituminous coal from Cerrejon in Colombia. Overall, it was found that operation was stable and loss of char to the air reactor was small, meaning that the CO2 capture efficiency was high (up to 90% at temperatures close to 950 degrees C in the fuel reactor). Gas concentration measurements showed the presence of unconverted CO, H-2 and CH4 corresponding to an oxygen demand of around 20%, depending on the fuel reactor temperature. In addition, a residence-time analysis was conducted from a batch experiment, enabling an estimation of the mass flow of oxygen carriers through the system using the riser pressure drop in the air reactor. (C) 2013 Elsevier Ltd. All rights reserved.