InAs thin films have been prepared by coevaporation. Hall mobilities up to 8000 cm2∕V‐sec have been obtained in films 3000‐Å thick, and 3000 cm2∕V‐sec in 1000‐Å films. Field‐effect transistors have been fabriacted of such films, exhibiting good saturation in both enhancement and depletion modes of operation. Field‐effect mobilities of 1800 cm2∕V‐sec, transconductances of 10,000 μ‐mhos and gain‐bandwidth products of 8 MHz were obtained in devices with a 100‐μ source‐drain spacing. Performance in the GHz region is predicted for devices of suitable geometry.