Bionanocomposites are a novel class of nanosized materials in the modern day world. The terminology “bionanocomposites” is introduced several years ago to classify an emerging class of biohybrid materials. Bionanocomposites are the com­bination of biopolymers such as proteins, polysaccharides, nucleic acids, etc. with a reinforcing agent having at least one dimension in the nanometer range. The rein­forcing agent may include plant fibers and by products from lignocellulosic renew­able resources or synthetic inorganic fraction of finely divided solids, spanning from clays to phosphates or carbonates, whose origin can be either natural or synthetic. The most important challenge in bionanocomposites is to achieve materials with improved performance characteristics, by the elusive management of the individual properties of the incorporated components. There are some similarities of bionano­composites with nanocomposites prepared by using commodity polymers but also have fundamental differences in the methods of preparation, functionalities, proper­ties, biodegradability, and applications. Processes and structure of bionanocompos­ites are regulated by water that is added in an amount to only hydrate functional groups in the carbohydrate macromolecule. In particular, the biodegradability and biocompatibility nature of biopolymers, along with the thermal and mechanical properties of the reinforcing counterpart, bridge the gap between functional and structural materials.114117 Engineered biopolymer-layered silicate nanocomposites are reported to have markedly improved physical properties including higher gas barrier properties, tensile strength, and thermal stability.118120 Chemically treated nanoscale silicate plates incorporated with appropriate polymers can provide ef­fective barrier performance against water, gases, and grease.121 These hyper-platy, nanodimensional thickness crystals create a tortuous path structure that inherently resists penetration.