Stainless steel and its alloys are widely used as a corrosion-resistant material in RO and desalination plants. However, these alloys have shown variable corrosion performance in chloride containing environments. Localized corrosion attack of some of these alloys, particularly in a welded metal region and heat affected zone are not uncommon. In duplex stainless steel (DSS) the volume fraction of the austenite phase tends to decrease in weldement compared with that of base metals because of the rapid cooling from a ferrite mono-phase temperature. This change of microstructure in welded metal affects (decreases) the mechanical and corrosion properties of DSS. A surface potential characterization of welded metal was established for a laser-welded DSS with 22Cr, 4.3Ni, 3Mo and 0.17N(2) using a modified surface potential mapping technique (SCM). It is evident from potential mapping tests that the welded metal is more anodic to the base metal in ferric chloride solution. The welded metal potential maps showed significant micro-galvanic interaction between ferrite and austenite phases. The results also showed that the modified SCM technique alone or in conjunction with other tests such as ASTM G48 could offer significant assistance as a laboratory diagnostic tool for decision-makers with regard to materials selection and early pit detection.