The corrosion of reinforcing steel in concrete partially submerged in salt water has been investigated using concrete slabs containing longitudinal rebars divided into elements with independent electrical connections. Open circuit potential, interelement current, concrete conductance, and electrochemical impedance measurements have been conducted while specimens were exposed to water containing chlorides over a period of about one year. Direct observations of corrosion and concrete characteristics were conducted at the end of the experiment. Corrosion tended to initiate at the evaporation zone of the vertical slabs, where chlorides accumulated. Once active corrosion started, a macrocell developed with the small portion of the bar below the water surface acting as an electron source. Evaluations of the damage from macrocell current and electrochemical measurements were in rough agreement with direct estimates of sound metal loss based on after-exposure examination. In bars where the separate elements were kept electrically isolated, corrosion proceeded at a higher rate at those elements near the evaporation zone. The results have been used to propose a mechanism for corrosion initiation and propagation in partially immersed reinforced concrete members.