This part of IEC 61234 describes the test method for the determination of the hydrolytic stability of plastic films subjected to the simultaneous influence of water and high temperature. With this test method, the irreversible changes of the mechanical and electrical properties are measured. The test method is applicable to films up to 250 micro m thick. Although this method was developed for electrically insulating plastic films, as specified, for example, in the series of IEC 60674, it may be appropriate for other types of plastic films.