In this work, mesoporous In2O3 nanorods composed of many small well-aligned crystal nanostructures have been fabricated by a simple sol−gel process, with block copolymer PE6800 as a soft template controlling their morphology. The effects of the experimental parameters such as the concentration of PE6800, the dosage of InCl3·4H2O, reaction temperature, and pH values were investigated by a series of experiments. The as-synthesized mesoporous In2O3 nanorods showed excellent gas-sensing properties to C2H5OH in terms of sensor response and selectivity.