The polypyrrole/p-InP structure has been fabricated by the electrochemical polymerization of the organic polypyrrole onto the p-InP substrate. The current-voltage (I-V)l capacitance-voltage (C-V), and capacitance-frequency (C-f) characteristics of the PPy/p-InP structure have been determined at room temperature. The structure showed nonideal I-V behavior with the ideality factor and the barrier height 1.48 and 0.69 eV respectively. C-f measurements of the structure have been carried out using the Schottky capacitance spectroscopy technique and it has been seen that there is a good agreement between the experimental and theoretical values. Also, it has been seen that capacitance almost show a plateau up to a certain value of frequency, after which, the capacitance decreases. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the p-InP that can follow the a.c. signal. The interface state density N-ss and relaxation time T of the structure were determined from C-f characteristics. (c) 2006 Wiley Periodicals, Inc.