Urease (urea amidohydrolase; E.C. 220.127.116.11) catalyses the hydrolysis of urea to carbon dioxide and ammonia. This enzyme has a long history. It was the first enzyme to be crystallized by J.B. Sumner (in 1926) for which the Nobel Prize was awarded in 1946. His discovery of the crystallized form of this protein struck the first major blow against the hypothesis that enzymes are non-protein catalysts. The second breakthrough was in 1975 where presence of nickel at the active site was reported. Till date there is no report on another Ni containing enzyme in the plants. The third achievement in the study of urease was the X-ray crystal structure of the enzyme from Klebsiella aerogenes at 2.0 Å resolution revealing the intimate details of the molecular geometry at the active site (Jabri et al., 1995). This thesis details the purification, physico-chemical characterization of urease from a commonly available local source, the dehusked seeds of Cajanus cajan L and the analytical applications of immobilized preparations.