Because of the continually rising levels of CO2 in the atmosphere, research for the conversion of CO2 into fuels using carbon-neutral energy is an important and current topic in catalysis. Recent research on molecular catalysts has led to improved rates for conversion of CO2 to formate, but the catalysts are based on precious metals such as iridium, ruthenium and rhodium and require high temperatures and high pressures. Using established thermodynamic properties of hydricity (Delta G(H)(-)) and acidity (pK(a)), we designed a cobalt-based catalyst system for the production of formate from CO2 and H-2. The complex Co(dmpe)(2)H (dmpe is 1,2-bis(dimethylphosphino)ethane) catalyzes the hydrogenation of CO2, with a turnover frequency of 3400 h(-1) at room temperature and 1 atm of 1:1 CO2:H-2 (74 000 h(-1) at 20 atm) in tetrahydrofuran. These results highlight the value of fundamental thermodynamic properties in the rational design of catalysts.