The development of large-area, low-cost electronics for flat-panel displays, sensor arrays, and flexible circuitry depends heavily on high-throughput fabrication processes and a choice of materials with appropriate performance characteristics. For different applications, high charge carrier mobility, high electrical conductivity, large dielectric constants, mechanical flexibility or optical transparency may be required. Although thin films of metal oxides could potentially meet all of these needs, at present they are deposited using slow and equipment-intensive techniques such as sputtering. Recently, solution processing schemes with high throughput have been developed, but these require high annealing temperatures (T_anneal>400 °C), which are incompatible with flexible polymeric substrates. Here we report combustion processing as a new general route to solution growth of diverse electronic metal oxide films (In₂O₃, a-Zn–Sn–O, a-In–Zn–O, ITO) at temperatures as low as 200 °C. We show that this method can be implemented to fabricate high-performance, optically transparent transistors on flexible plastic substrates.