Pseudobinary molybdenum cluster tellurides (Chevrel phases) with mixed transition metal clusters of the type M(x)Mo(6-x)Te(8) (M = Pt, Os, Ru, Rh) and the binary phase Mo6Te8 have been synthesized, structurally characterized and electrochemically investigated with respect to their electrocatalytic properties for oxygen reduction. A correlation of the number of electrons per cluster unit (NEC) with the open circuit potential (o.c.p.) in saturated oxygen electrolyte was found. The limitation of the o.c.p. values are due to the mixed potential developed with each electrode material due to molybdenum oxidation. The lowest corrosion tendency and highest catalytic activity are found in the telluride phases when NEC (in the valence band) approaches 24.