A Riser Simulator was employed to study OCM. An automatic injection was designed to inject reactants and to sample products. Sm2O3 catalyst was developed to suit the staged oxygen injection concept. Systematic runs were carried out between 500 and 700 degrees C. A three lump reaction model, including C-2 and COx lumps, was considered. Simulated C-2 selectivities showed 25% for co-feeding (one injection) and 58% for staged oxygen (several injections).