The superoxide dismutase (SOD) family of proteins are necessary to protect oxygen-utilizing cells from the toxicity of reactive oxygen species. The delivery of SOD into tissues is severely limited by its size and biochemical properties. A cell-membrane-permeable SOD, SOD-TAT, has been demonstrated to have the ability to be directly transduced into mammalian cells. In this study, the SOD-TAT fusion protein was expressed, purified and crystallized. Crystals of the SOD-TAT fusion protein diffracted to 3.20 Å resolution and belonged to space group C121.