The polyaniline/p-Si Structure has been made by the electrochemical polymerization of the organic polyaniline onto the p-Si substrate. The reverse bias capacitance-voltage (C-V) characteristics of the structure have been determined at different temperatures. The 1/C(2)-V plots of the structure are non-linear and the Values of the diffusion potentials are exceeding the band gap value and these characteristics have been attributed to the presence of the excess capacitance due to the space charge and interface states in the depletion layer. Non-linear 1/C(2)-V plots showing Curvature concave downwards have been transformed into linear 1/(C-C(0))(2) vs. V plots by determining the excess capacitance, C(0). Then. some junction parameters, such as the barrier height, have been calculated. (C) 2008 Published by Elsevier B.V.