Due to its unique electronic and optical properties, ternary indium–gallium–zinc oxide (IGZO) is applied in flexible and transparent electronics, including in particular thin-film transistors. The IGZO physical properties depend on the synthesis conditions and the ratio of its main constituents (indium, gallium, zinc, and oxygen) and various dopants. A method to synthesize samples of the In1–2xGaSnxZn1+xO4 series (x = 0.05, 0.10, 0.15) by nitrate-organic gel combustion is described. In this approach, the synthesis can be carried out in a shorter time and at lower temperatures compared to alternative methods reported in the literature. The resulting samples are studied by powder X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The homogeneity of the samples is proved at x = 0.05 and 0.10.