Acacia nilotica is a multipurpose woody tree grown world over and it is rich in tannin, which plays a major role in the litter degradation and nutrient recycling of the tree parts. In the present study, detailed analysis of the tannin in the different parts of the tree and litter was conducted and the contents were compared with other chemical constituents. The protein precipitating ability of the tannins was also determined to understand the biological effects of tannins when introduced in soil. The study indicated that the tree comprised of two types of tannins namely condensed (CT) and hydrolysable (HT). Leaves had more HT and barks had more CT. HT imparted much to the protein precipitation property of the tannins. As most of the CT % was fibre bound they might not have contributed to protein precipitation ability but on the other hand may become difficult to be decomposed. A strong negative correlation was seen between the total nitrogen content and CT content. CT showed positive correlation with fibre bound N and lignin.