A comprehensive review of the large number of contact materials that have been proposed for vacuum interrupter applications is presented. These contact materials are classified into four major groupings: 1) pure metals, 2) alloys, 3) mixtures of refractory materials and good conductors, and 4) mixtures of semirefractory materials and good conductors. Experimental results are presented that give a comparison of how the different materials perform for different circuit interruption conditions. Four performance criteria are used to provide this comparison: a)contact resistance, b)current interruption ability, c) current chop, and d) contact welding.