Pitting potential (Ep) and degree of sensitization (DOS) of a supermartensitic stainless steel (SMSS) were determined on specimens heat-treated at different tempering temperatures (550°C, 575°C, 600°C, 625°C, 650°C, or 700°C). The effect of pH (pH 6 and pH 8) on the Ep obtained in a 3.5 wt% NaCl solution, as well as the correlation between Ep and DOS obtained in 0.5 M H2SO4 + 0.01 M KSCN solution, was studied. The results showed correlation between Ep and DOS values, the samples with the higher DOS values being the ones with the lower Ep. A mechanism was proposed that would explain the correlation of the presence of reversed austenite formed during tempering, Ep, and DOS.