In this work, single-crystalline InVO4 nanorods were first prepared by a solution-phase approach in the presence of an ionic liquid 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM] [BF4]), which could act as a cosolvent and a structure-directing agent in the system. The diameters could be varied easily by subjecting the mixed precursor to different heat treatment temperatures or different durations of time in an oven. Unlike other nanorods synthesized by the microwave-assisted method, the InVO4 nanorods were stable under electron beam irradiation.