In this paper, 5,6,11,12-tetraphenylnaphthacene (rubrene) was prepared on n type GaAs (100) substrate by spin coating. The device parameters of Al/rubrene/n-GaAs (100) Schottky diode have been investigated by means of current-voltage (I-V) characteristics in the temperature range 100-300 K by steps of 50 K and capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics at 1 MHz and 300 K. It was observed that ideality factors increased and barrier heights decreased with the decreasing temperature. The observed anomaly of temperature dependence of Schottky barrier height and ideality factor are explained by Gaussian distribution of Schottky barrier height in the same temperature ranges. Al/rubrene/n-GaAs Schottky barrier diode has been shown to have a Gaussian distribution with mean barrier height (Φ¯B) of 1.076 eV and standard deviation (σs) of 0.119 V. Schottky barrier height (ΦB), series resistance (Rs), and the density of interface trap states (Ns s) of the diode were calculated as 1.004 eV, 1.18 k Ω and 2.145 × 1011 eV-1 cm-2 for 1 MHz, respectively.