Urease E.C.3.5.1.5 acts as a catalyst in the hydrolysis of urea to ammonia and carbon dioxide. Presence of this enzyme can increase the rate of reaction by 10(14). Urea levels are vital in medical diagnosis, environmental and bioindustrial analysis. This paper presents an innovative technique for enzyme immobilization. Nanocomposite fibers of urease and polyvinylpyrrolidone (PVP) were prepared by the electrospinning technique. The nonwoven mat formed has potential as a urea biosensor. Its advancements over prior technology are faster response time, sensitivity to lower concentrations of urea, and a more versatile design. (c) 2004 Elsevier B.V. All rights reserved.