Al/maleic anhydride (MA)/p-Si metal polymer semiconductor (NIPS) structures were prepared on p-Si substrate by spin coating. Device parameters of Al/MA/p-Si structure have been determined by means of capacitance voltage (C-V) and conductance voltage (G-V) measurements between 700 kHz and 1.5 MHz and current voltage (I-V) measurements at 300 K. The parameters of diode such as the ideality factor, series resistance, barrier height (BH) and fiat band barrier height were calculated from the forward bias I-V characteristics. The investigation of interface states that density and series resistance from C-V and G-V characteristics in Al/NIA/p-Si device has been reported. The frequency dependence of the capacitance could be attributed to trapping states. Several important device parameters such as the BH Ob, fermi energy (EF), diffusion voltage (VD), donor carrier concentration (N-D) and space charge layer width (W-D) for the device have been obtained between 700 kHz and 1.5 MHz. The I-V, CV-f and G-V-f characteristics confirm that the parameters like the BH, interface state density (DO and series resistance (R-s) of the diode are strongly dependent on the electrical parameters in the MPS structures.