A polyaniline/p-Si/Al MIS device has been fabricated by forming a polyaniline layer on Si by using the electrochemical polymerization method. The conductance-voltage and capacitance-frequency measurements have been performed as a function of temperature. The capacitance of the device decreased with increasing frequency. The increase in capacitance results from the presence of interface states. The peaks have been observed in the conductance curves of the device and attributed to the presence of an interfacial layer between polyaniline and p-Si. For each temperature, the plot of series resistance/voltage gave a peak. The voltage and temperature dependence of series resistance has been attributed to the particular distribution density of interface states and the interfacial insulator layer. (C) 2012 Elsevier Ltd. All rights reserved.