In this work, a unique electrode based on aminopropyl-triethoxysilane ( APTS)-coated porous silicon(PS) substrate has been fabricared and used as a urea-sensitive electrode after urease immobilization. PS substrate was formed by electrochemical anodization in an etching solution composed of HF and ethanol. APTS layer was formed on the PS surface by coating and heating at 1053K in argon atmosphere. Urease immobilization was carried out by immersing the APTS/PS in urease solution. The immobilized system gives linear response for concentrations of urea ranging in values between 3.6×10−3 and 8.0×10−3 mol dm-3, studied with voltammetry. The surface of biofunctionized porous silicon has thus provided a suitable environment for urease with 15 days retention of its activity. The molecular structure on the PS surface was characterized with infrared (IR) technique. The change in the surface morphology has been studied by scanning electron microscopy and it is observed that the immobilized system has successfully retained urease.