The green crab (Carcinus maenas) shell is the potential source for numerous bio-products that are to be utilized in a variety of biomedical and biotechnology applications. Chitin and Chitosan are the most important materials from crab shells and its application in the design of various medical devices such as drug delivery vehicle and tissue engineering construct. Even though the well established extraction protocol for chitin/Chitosan from crab shell is available, however, there are large usage of harsh chemicals with high concentration such as 2M Sodium Hydroxide solution and 2M hydrochloric acid for chitin extraction. As a consequence, These harsh chemicals affect not only affect the quality of chitin/chitosan polymer also produce numerous environmental problems such as increasing acidity and total dissolved solids in waste water by neutralizing acid with an alkali or vice versa. The most important focus of this investigation is to contribute the interpretation of the deprotenization of the grab shells using various concentration of sodium hydroxide solution and contact time at different temperatures. The protein leached from the grab shell is measured by reading absorbance at 280 nm in UV-Visible spectrophotometer. Furthermore, the percentage removal of protein from the crab shell at various concentration of Sodium hydroxide is carried out and evaluated based on the dry weight of the crab shell. The optimized temperature of deprotenization is found and commented. In addition to that, the kinetic limitation of de-proteinization is mentioned using experimental data. To conclude, the effective de-protenization of green crab shell is carried out in 1M NaOH at 45°C for extraction of chitosan with optimum quantity from green crab shells.