We have developed novel nanostructured PANI/ZnO and PANI/MnO2 electropolymerized stainless steel electrodes as highly sensitive biosensors. At first, nanostructured ZnO and MnO2 have been synthesized chemically and polyaniline nanocomposites with different weight percentage (5, 10 and 15%) were electrochemically deposited onto the stainless steel electrode. These modified electrode surfaces were used for immobilizing the Urease by physical absorption method. Then, nanostructural characterization of the sensor's surface were performed using SEM, FTIR and XRD techniques to understand the surface morphologies of the sensitive materials to better evaluate film suitability for biosensing. Also the characterization such as Cyclic Voltametry, Chronoamperometry and EIS were performed in order to evaluate the electrochemical performance of the constructed biosensors.In third stage, the developed sensors were tested towards detection of Hg (II) and Pb (II) heavy metal ions.