The method of doping the trivalent cation into copper-based catalyst for methanol synthesis is effective in enhancing catalytic activity. The form of chromium in the catalyst and the nature of promotion effect as well as its relation to catalytic activity after doping Cr2O3 into Cu-ZnO-Al2O3 has been studied by XRD, ESR,TPR and the determination of catalytic activity. The results showed that chromium exists in the ZnO lattice as both Cr3+ and ZnCr2O4. Catalytic activity of Cu-ZnO-Al2O3-Cr2O3 catalyst for methanol synthesis and ESR intensity of the monovalent defect induced by dissolving Cr3+ into ZnO lattice as well as other ESR species in catalyst ale well interrelated. The catalyst containing one per cent of Cr3+(atomic ratio) has the highest catalytic activity
