We have investigated the electrical, structural and surface morphological characteristics of Pt/Re/Au ohmic contacts to moderately doped p-type GaN (1.13 x 10(17) cm(-3)) before and after annealing. It is shown that the current-voltage (I-V) characteristics of the as-deposited contacts is improved upon annealing at 600 degrees C for 1 min under N-2 ambient. Pt (20 nm)/Re (30 nm)/Au (80 nm) contact produces a specific contact resistance (p(c)) of 1.4 x 10(-3) Omega cm(2) when annealed at 600 degrees C. However, annealing the sample at 800 degrees C results in the degradation of the I-V behavior. Auger electron microscopy and glancing angle XRD are used to investigate interfacial reactions between the Pt/Re/Au and p-GaN layers. It is shown that Ga-related phases such as Ga3Pt5, GaPt2, Ga3Re, GaAu2 and GaAu are formed upon annealing at 600 degrees C. The AFM results showed that the surface morphology of the as-deposited contact is improved (with a RMS roughness of 2.2-1.4 nm) with increasing temperature up to 600 degrees C and degraded when the contact annealed at 800 degrees C (with RMS roughness of 8.6 nm). Published by Elsevier B.V.