Chitin a natural polymer extracted commercially from the shells of crustaceans such as prawns, crabs, krill, insects and shrimps. Chitosan is prepared from chitin by partially deacylating its acetamido groups with a strong alkaline solution. Chitin and chitosan have a wide variety of applications such as wastewater treatment which decreases the Chemical Oxygen Demand [COD] and used in preventing infections of wounds and also as a food supplement, which lower plasma cholesterol and improves the HDL cholesterol. Besides these applications chitosan has a few drawbacks like acidic solubility, low thermal and mechanical stability. To rectify these drawbacks of chitosan can be modified physically and chemically. In this present study, the biopolymer chitosan was cross linked with glutaraldehyde and blended with the copolymer polyacrylonitrile in different ratios and the prepared blend was characterized by FTIR, DSC, TGA and XRD studies. The prepared cross linked Chitosan-Poly acrylonitrile blend has good thermal stability and better adsorption capacity.