In this research, we evaluated the electrical properties of polycrystalline-gallium-oxide (Ga₂O₃) thin films grown by mist-CVD. A 500~800 nm-thick Ga₂O₃ film was used as a channel in a fabricated bottom-gate MOSFET device. The phase stability of the β-phase Ga₂O₃ layer was enhanced by an annealing treatment. A Ti/Al metal stack served as source and drain electrodes. Maximum drain current (I_D) exceeded 1 mA at a drain voltage (VD) of 20 V. Electron mobility of the β-Ga₂O₃ channel was determined from maximum transconductance (gm), as approximately, 1.39 cm²/Vs. Reasonable device characteristics were demonstrated, from measurement of drain current-gate voltage, for mist-CVD-grown Ga₂O³ thin films.