Effect of a crevice on the breakdown potentials (E-b) of carbon steel specimens in pH 12.6 saturated calcium hydroxide (Ca[OH](2)) solution (SCS) and pH 13.6 simulated concrete pore solution (SPS) with 0.01 M to 1.0 M chloride concentration ([Cl-=]) was studied with potentiodynamic polarization. The presence of a crevice substantially lowered (by similar to 0.2 V) the Eb in SCS when [Cl-] greater than or equal to 0.1 M. In SPS, passive film breakdown did not take place up to the oxygen evolution potential (OEP) in the absence of a crevice. However, corrosion developed in the crevice at potentials similar to 0.5 V below the OEP when a crevice was introduced and [Cl-] greater than or equal to 0.1 M.