Nanorods of SnO2 have successfully been prepared by calcining precursors that are produced in inverse microemulsions. The water/oil microemulsions used to prepare the precursors form an ideal nanostructural reactor for producing monodispersed nanoparticles, which can then decompose to form SnO2 nanorods (see Figure). The mechanism of formation of the nanorods by nucleation and growth processes is discussed.