MgIn₂O₄ films were reactively deposited with assistance of rf discharge at an oxygen pressure of 4 × 10^-2 Pa and at a substrate temperature between room temperature and 550°C. The dependence of the structure of the films and their physical properties on the substrate temperature was studied. It was found that crystallized films were deposited at 250 and 350°C, while films were almost amorphous at room temperature. The crystallinity of the films was also reduced at and above 450°C because of deviation of the film composition from stoichiometry. The crystallized films were highly transparent with an average transmission of about 80 %, and by heat treatment in H₂ gas, became very conductive having a resistivity of about 8 × 10^-2Ωcm.