This International Standard describes a test method for evaluating the heat resistance of protective clothing materials or items and equipment when exposed in a hot air circulating oven. The method is intended to evaluate physical changes in a material at a given exposure temperature. Materials are evaluated for visible changes or subjected to a material property measurement following heat exposure. This test method also enables the measurement of shrinkage that occurs as a result of the heat exposure. Different procedures are provided depending on the type of the protective clothing material or item being tested.