It is important to investigate the factors that influence the metal-semiconductor interfaces. Some of these factors are the effects of the semiconductor surface and barrier metal. Therefore, in this work we have investigated the influences of hydrogen pre-annealing and barrier metal thickness on the Au/n-GaAs Schottky barrier diodes. Having performed current-voltage and capacitance-voltage measurements, the values of the ideality factor and barrier height for the un-annealed diodes range from 1.14 and 0.855 eV (for 5 nm) to 1.08 and 0.794 eV (for 100 nm), respectively. Also, the same parameters for the H-2 pre-annealed diodes range from 1.78 and 0.920 eV (for 5 nm) to 1.11 and 0.774 eV (for 100 nm), respectively. (c) 2008 Elsevier B.V. All rights reserved.