A novel experimental technique for making electrochemical measurements on individual phase or isolated regions of a metal or alloy is reported. The technique, called Selective Masking by Photolithography (SMP), uses a hardened photoresist coating to mask the excluded portions of the sample and 355 nm laser pulses are employed to expose individual grains or regions of interest. The size of the exposed area can range from tens of microns to millimeters. Localized electrochemical DC and AC measurements and critical pitting temperature determinations for the two phases in a duplex stainless steel were used to show the utility and viability of SMP. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.008201jes]