The rate of methanol synthesis over a Cu(100) single crystal from a 1 : 1 mixture Of CO2 and H-2 has been measured at a total pressure of 2 bar and a temperature range of 483-563 K. At these conditions the apparent activation energy is determined to be 69 kJ mol-1, and at 543 K the turnover rate is 2.7 x 10(-4) (site s)-1. A kinetic model for the methanol synthesis is presented. Predictions from this model are in good agreement with the rates of methanol synthesis observed on real catalysts at industrial conditions.