Polypyrrole (PPY) is one of the most promising materials for multifunctionalized applications. Preparation, characterization, properties and applications of PPYs are reviewed in this paper. In addition, the PPY composites are described in detail according to the synthetic methods and their applications. At the same time, effects of various parameters such as doping anions, additives, and oxidant, on the PPY properties are also concerned. The PPY films and membranes used for ion exchange, pervaporation, and gas separation are mentioned. In this review, ion exchange membranes are highlighted. Moreover, the further investigation of PPY composite membranes for oxygen enrichment is predicted. A total of 117 references are cited.