The pitting corrosion characteristics of four boride-strengthened microcrystalline alloys, two Ni-based and two Fe-based, were studied in 1 M NaCl solution at 25–80°C, using the cyclic potentiodynamic technique. Two commercial materials, namely Alloy 600 and AISI Type 316 stainless steel, were also tested for comparison. As in the case of conventional materials, a higher content of Cr in the microcrystalline alloy was found to provide greater resistance to pitting. Mo contents also had beneficial effects. Alloys with the highest Cr contents exhibited the highest pitting potential in each group of the materials tested. Because of the formation of pits covered with Cr-rich oxidation products, repassivation of pits on these alloys was more difficult than on those with less Cr. The presence of boride precipitates in microcrystalline alloys appeared to promote rather than inhibit pit initiation and growth.