This compilation of test methods applies to both reverse osmosis and electrodialysis membranes currently available in the commercial market place. The techniques described can be used for quality control of manufactured products, newly purchased materials and those membrane products which have been in service. The procedures for the physical and chemical properties have been presented separately; however, in actual fact these properties are interrelated. The physical properties apply to equipment design and in addition they impact on the application to some extent. Some chemical methods have been included to provide an overall treatment. For those familiar with membrane technology, it will be apparent that many of the procedures described can be modified to reflect or nearly duplicate a particular application. In most cases this can be accomplished by the prudent choice of electrolyte, concentration, time or temperature used. These methods cannot be applied to those reverse osmosis devices supplied as hollow fiber modules. Operating characteristics of these devices have been addressed by ASTM. In general, however, this type of equipment must be tested as a complete installation by following the supplier's instructions. This type of detailed operation is outside the scope of this presentation.