A new type of GaAs electro-optic directional-coupler switch for monolithic integrated optics has been proposed and demonstrated. The switch was fabricated from a pair of closely spaced low-loss (α≃2.2 dB/cm at 1.15 µm) single-mode rib-waveguides with Au Schottky barriers. A 30 dB extinction ratio in the input channel was measured at a reverse-bias voltage of24 V and the switches have a potential 3 dB-bandwidth of 4 GHz. By the bends of rib-waveguides, both waveguides at input and output end faces were separated by 22 µm, in order to form an optical switching network and couple to optical fibers.