The cement and lime industries are major contributors to the anthropogenic CO2 emissions to the atmosphere. By combining the CO2-releasing calcination of CaCO3 with the CO2-consuming dry-reforming of CH4, and by further combining these endothermic reactions with the exothermic partial oxidation of CH4, a single thermoneutral process can be designed for co-producing CaO and syngas in an authothermal reactor. Syngas can be further processed to H-2, methanol, or Fischer-Tropsch chemicals. The conditions for thermo-neutrality are determined by thermo, chemical equilibrium calculations. Such combined processes could achieve considerable CO2 emission avoidance as well as fuel saving relative to the conventional production of CaO and syngas. A preliminary evaluation indicates favorable economics for the co-production of CaO and hydrogen or methanol from CaCO3 + O-2 + H2O and natural gas (NG) or coal. (C) 2005 Elsevier Ltd. All rights reserved.