Ion implantation of different metals in Pb and Pb-4% Sb has been found to improve the open-circuit corrosion resistance of the two metals in 5M H2SO4. Titanium ions were implanted under different conditions of ion dose and ion energy. Optimum implantation conditions resulted in an up to 72-fold reduction of corrosion currents. The implantation of V, Cr, Ni, and W has been investigated for one implantation condition and has also resulted in decreased corrosion currents. The corrosion behavior was characterized by the current response to small anodic potential steps. Surface analysis and depth profiles have shown the importance of the spacial distribution of the implanted ions for their effects on the anodic and cathodic parts of the corrosion reactions.