Silicon nanowires (SiNWs) are grown by Chemical Vapor Deposition on highly doped silicon wafer via localized gold catalysis with monitored length, diameter, density and doping level. This work highlights the influence of SiNWs morphological characteristics on their electrochemical performances and analyses in details the key role of the doping level for exhibiting a typical double layer capacitive behavior. The electrochemical performances of silicon and SiNWs electrodes are evaluated in an organic electrolyte by electrochemical impedance spectroscopy and cyclic voltammetry. Electrode capacitance has been improved up to 440µFcm−2, i.e. about 75 fold that of bulk and about 10 fold that of the one previously reported.