This document specifies the test methods for the pH value of friction materials, including instrumentation equipment and materials, specimen preparation, test steps, result representation and test report. It is suitable for the determination of the pH value of brake linings and clutch surfaces for automobiles. Miscellaneous type friction materials can be referred to for use. Cited standards on laboratory water, numerical revision rules and buffer solution preparation methods for pH value determination. Required instrumentation equipment includes pH Meter, beaker, Balance, thermostatic drying oven, drying device, measuringflask, mercury-filledthermometer, absoluteethanol and distillation water.