Polymeric compounds are generally blended with inorganic/organic materials to prepare composites to tailor the desired properties for specific requirements. The present book reviews new research in the fields of composite green polymers for environmental applications, polyaniline based composites for wastewater treatment, smart polymeric coating materials, polymer decorated bimetallic nanosorbents for dye removal, fuel cell materials, polymeric membranes, green bio-nanocomposites and polymer based catalysts.