A new two dimensional (2D) material—germanane—has been synthesised recently with promising electrical and optical properties. In this paper we report the first realisation of germanane field-effect transistors fabricated from multilayer single crystal flakes. Our germanane devices show transport in both electron and hole doped regimes with on/off current ratio of up to 10e5(10e4) and carrier mobilities of 150 cm2 (Vs)−1(70 cm2 (Vs)−1) at 77 K (room temperature). A significant enhancement of the device conductivity under illumination with 650 nm red laser is observed. Our results reveal ambipolar transport properties of germanane with great potential for (opto)electronics applications.