Lignocellulosic - Coir fibers are the potential biodegradable and renewable material is used to make composites for various applications such as insulation, packaging, automobile parts, construction etc,. It is essential to do some chemical modifications to achieve better physical properties and thermal stability. This book highlights the properties of virgin and chemically treated coir fibers. The influence of alkali and aldehyde treatment on tensile strength and other properties are reported. Such type of chemical modifications are beneficial to improve the stability of coir fiber. Composites of polyvinyl alcohol have been developed by reinforcing the chemically modified coir fibers. Enhancement in the stability in terms of tensile properties is noticed. Finally, the applicability of the resulting composites is also reported in this book.