Experiments are described which attempt to exploit the redox or oxygen transfer mechanism of iron-catalyzed coal gasification by periodically alternating between an oxidizing and a reducing gas environment. A low-rank, Canadian coal was used and carbon dioxide was the oxidizing gas. A 15% increase in the yield of CO based on CO2 supplied compared to the steady-state operation of the gasifier was observed at 800 degrees C for a coal loaded with 3 wt % Fe using a cycle period of 60 s, The advantage for the modulation operation decreased with increasing temperature and became negligible at 900 degrees C.