he monograph demonstrates the results of recent years in the field of polymer composites based on a polymer matrix of various nature and oxide, metallic nanoparticles. The main methods of their preparation are summarize, the properties of the obtained materials and the possible areas of their application are described. Methods of surface modification of the nanoparticles which are the basic condition for obtaining materials with functional properties are carried out. The established relationships between the structure and physico-chemical properties of polyaniline nanocomposites make it possible to purposefully influence the process formation of nanostructured photoactive composites with a certain complex functional properties. Synthesized photocatalytic composites based on polyaniline and oxide nanoparticles can be used in the development of filtering membrane materials for cleaning from harmful and toxic substances of water and air, chemical sensors and electrochromic displays.