Eukaryotic iron superoxide dismutases (FeSODs) are homodimeric proteins that constitute a fundamental protection against free radicals, which can damage essential cellular mechanisms. The protein was cloned and overexpressed in Escherichia coli with an N-terminal His tag. Crystallization experiments of the protein resulted, after several refined screenings, in crystals suitable for X-ray diffraction analysis. The crystals belong to the monoclinic space group C2, with unit-cell parameters a = 82.54, b = 48.41, c = 64.28 A, alpha = gamma = 90, beta = 119.66 degrees, and contain one molecule per asymmetric unit. At cryogenic temperatures, the crystals diffracted to a resolution limit of 1.80 A using synchrotron radiation at the European Synchrotron Radiation Facility (ESRF).