A study on interface states density distribution and characteristic parameters of the In/SiO2/p-Si (MIS) capacitor has been made. The thickness of the SiO2 film obtained from the measurement of the corrected capacitance in the strong accumulation region for MIS Schottky diodes was 220 Å. The diode parameters from the forward bias I-V characteristics such as ideality factor, series resistance and barrier heights were found to be 1.75, 106-112 Ω and 0.592 eV, respectively. The energy distribution of the interface state density Dit was determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. The interface state density obtained using the I-V characteristics had an exponential growth, with bias towards the top of the valance band, from 9.44×1013 eV-1 cm-2 in 0.329-Ev eV to 1.11×1013 eV-1 cm-2 in 0.527-Ev eV at room temperature. Furthermore, the values of interface state density Dit obtained by the Hill-Coleman method from the C-V characteristics range from 52.9×1013 to 1.11×1013 eV-1 cm-2 at a frequency range of 30kHz-1 MHz. These values of Dit and Rs were responsible for the non-ideal behaviour of I-V and C-V characteristics. © 2008 Elsevier B.V. All rights reserved.