In this study, we investigated the electrical properties of the Au/P3HT/n-GaAs Schottky diode at room temperature by using current-voltage method. The values of ideality factor and barrier height of the diode were found to be 2.45 and 0.85 eV, respectively. n ideality factor greater than unity indicates that the diode exhibits non-ideal current-voltage behavior. This behavior results from the effect of series resistance and the presence of an interfacial layer. These values were also determined from the Cheung functions and the Norde method due to the non-ideal behavior of the diode and it was seen that there was an agreement with series resistance. Also the interface states energy distribution of the diode was determined from the forward bias I-V measurements by taking into account the bias dependence of the effective barrier height. The obtained electrical parameters of the Au/P3HT/n-GaAs Schottky diode are higher than that of the conventional Au/n-GaAs Schottky diodes.