This International Standard describes the procedure for determining the critical pitting temperature for stainless steels (austenitic, ferritic/austenitic, ferritic stainless steel) under potentiostatic control. The principal advantage of the test is the rapidity with which the critical pitting temperature can be measured in a single test. The critical pitting temperature, as determined in this International Standard, can be used as a relative index of performance, for example, to compare the relative performance of different grades of stainless steel. The test described in this International Standard is not intended to determine the temperature at which pitting will occur in service.