Chemical Looping Steam Methane Reforming (CL-SMR) allows the production of high-quality syngas and H2, avoiding the energy penalty associated with further products separation and purification. Ca2Fe2O5 (C2F) has been recently considered as a viable oxygen carrier (OC) due to its good phase reversibility and low equilibrium pO2, but its applicability is limited by the slow reduction kinetics. In this work we report the selection and composition optimization of a catalyst-assisted oxygen carrier (OC) material prepared by simple physical mixing of C2F and Ni-loaded Ce1-xMxO2-δ (M=Al, Si, Zr, and Ni loading is 2.12% wt.). The co-presence of C2F and the catalyst in the same reactive bed effectively limited the carbon formation at low OC conversion degrees, as shown by comparing results from unstructured (physically mixed C2F and Ni-loaded Ce1-xMxO2-δ) and structured (layered) bed configurations. This phenomenon was attributed to a gas-mediated cooperative mechanism, in which carbon deposited on the catalyst is gasified in situ by H2O and CO2 generated on C2F, leading to a fast oxygen exchange and to a stable syngas production as long as lattice oxygens are available. At the 50th CL-SMR cycle, the composite OC produced 9.9 mmol/g of syngas in the reduction step with 86.9% CH4 conversion, and 5.3 mmol/g of H2 in the water splitting step with >99.9% purity. These values are comparable to other OC systems operating at higher temperatures and tested for a smaller number of cycles.