Ternary semiconducting oxide compound magnesium indium oxide films (MgIn(2)O(4)), manifesting high transparency were prepared by metal organic chemical spray pyrolysis technique. Precursors prepared for various cationic ratios of Mg/In=0.35, 0.40, 0.45 and 0.50 were thermally sprayed onto quartz substrates, decomposed at 450 degrees C and the spinel phase evolution was studied. X-ray diffraction, Rutherford backscattering and X-ray photoelectron spectroscopy studies have been conducted to confirm the formation of single-phase MgIn(2)O(4) films with Mg/In ratio 0.50. From optical transmission studies, the observed optical band gaps varied from 3.18 to 3.86 eV (0.35 < Mg/In < 0.5). The electrical conductivity variations of these films were measured in the temperature range between 30 and 150 degrees C by four-probe technique (34.07-1.44x10(-5) S cm(-1)) and the Hall coefficient showed n-type electrical conduction and high carrier concentration (0.16x 10(20)-0.89x (17) cm(-3)). (c) 2008 Elsevier B.V. All rights reserved.