Galactomannan is a biopolymer polysaccharides mostly obtained from Leguminosae plant have shown an interesting capability as drug carrier. In this study, galactomannan from the seeds ofLeucaenaleucocephalaknown locally as ‘petai belalang’ was obtained by water extraction. The galactomannan was characterized structurally by nuclear magnetic resonance (NMR) and fourier transform infrared spectroscopy (FTIR). Highly molecular weight of galactomannan, > 2.56 x 106Da, was successfully extracted from the plant. Total carbohydrate content of this polysaccharides is 74.84% and composition of galactose and mannose have been confirm by high performance liquid chromatography (HPLC) which is 36.67% and 38.17% respectively. M/G ratio was determined as 1:1. Hence, galactomannan has been successfully extracted from the seeds ofLeucaenaleucocephala.