In this paper we propose the exploitation of TiO2 nanotube arrays as biocompatible electrodes for implantable supercapacitors. TiO2 nanotubes are obtained by anodic oxidation of titanium foil and the assembly of the whole energy storage device is conducted using only biocompatible materials: PDMS is selected as packaging material both for its biocompatibility and easy fabrication process, glass-fiber filter acts as separator and the Dulbecco’s Phosphate Buffered Saline solution as physiological electrolyte. Electrochemical characterizations of the proposed flexible device reveal promising performances of TiO2 nanotubes array for future implantable supercapacitors.