Abstract: The cDNA encoding human Cu/Zn superoxide dismutase was amplified by RT PCR using the total RNA of human liver as the template, and was cloned into the plasmid pBluescript SK. The sequence of the cloned h SOD cDNA was consistent with the reported data. The h SOD cDNA was cloned into plant expression vector PBICuS. The recombinant plasmid PBICuS was introduced into Agrobacterium tumefaciens LBA4404. Potato plants were transformed via Agrobacterium tumefaciens mediated procedure. It was confirmed by PCR and Southern blot analysis that the human Cu, Zn SOD gene was expressed in potato at high level. The expression product was characterized by Western blot analysis. The SOD activity of transgenic potatoes was detected by the inhibition of nitro tetrazolium (NBT) reduction. The activity in tubes was 1 011 U/g(FW) and the activity in leaves was 1 066.6 U/g(FW).