The synthesis of methanol by the hydrogenation of CO2 over Zn-deposited and Zn-free single-crystal copper surfaces has been studied using an x-ray photoelectron spectroscopy apparatus combined with a high-pressure how reactor (18 atm). The order of plane for the catalytic activity was (110)>(311)>(100)>(111) for Zn-free copper surfaces. The Zn-deposited Cu(111) (theta(Zn)=0.19) was 13 fold more active than the Zn-free Cu(lll). The activation energy for the methanol synthesis (73-84 kJ/mol) was close to each other regardless of the surface structure or the presence of Zn. It was shown that the Zn deposited on Cu(lll) acted as a promoter for the methanol synthesis, while the Zn on Cu(110) and Cu(100) had no such a promotional effect. On the postreaction surfaces of Zn-deposited and Zn-free copper samples, a small amount of formate species was always detected which was more stable than that on clean Cu surfaces. This formate species’s coverage was proportional to the activity for methanol formation.