Apoenzyme, containing ≤0.1 zinc atoms and ≤0.2 Fe atoms per subunit and with ≤3% of the phosphatase activity, has been prepared from native red kidney bean purple phosphatase. Treatment of this apoenzyme with Fe3+ or Zn2+ separately gave very little recovery of activity, whereas treatment with both Fe3+ and Zn2+ resulted in complete restoration of activity, indicating that both metal ions are essential. ZnFe enzyme with close to one iron and one zinc atom per subunit has been reconstituted by this procedure. Essentially full reactivation was also achieved by addition of Fe3+ together with Fe2+ or Co2+ to the apoenzyme; Fe3+ and Cd2+ gave 27% restoration of activity, whereas Fe3+ with Mn2+, Cu2+, Ni2+ or Hg2+ gave little or no increase in activity. Kinetic parameters for the hydrolysis of p-nitrophenyl phosphate and ATP by the FeFe derivative are reported. © 1988.