Pt/Ti contact to variety of binary III-V and related ternary semiconductor materials were established. These contacts were formed by electron beam evaporation and subsequent rapid thermal processing in order to sinter the metal-semiconductor systems. The contacts to p-type InAs, GaAs, In0.53Ga0.43As, In0.52Al0.4As and Ga0.7Al0.3As were ohmic, as a result of heating at temperatures of 450°C or higher. The Pt/Ti contacts to InP and GaP displayed Schottky behavior as-deposited and preserved the rectifying nature through heat treatments, regardless of the processing conditions. The electrical properties and the microstructure evolution in these 7 systems is discussed in this paper.