Well-defined faceted zinc stannate, including cubic ZnSnO₃ and octahedral Zn₂SnO₄, microcrystals were synthesized in a large scale by a one-step chemical solution route, in which the phase control was simply accomplished by only changing stannic precursors. These faceted cubic ZnSnO₃ and octahedral Zn₂SnO₄ microcrystals are easily converted to faceted hollow structures with a shape preserved through an acid etching process. Possible growth and etching mechanisms of these faceted microcrystals have been proposed. The hollow structures of zinc stannate were exploited as gas sensors and exhibit improved sensing performances to a series of gases (especially with regard to H₂S and C₂H₅OH); moreover, the sensitivity and recovery time of Zn₂SnO₄ hollow octahedral structures to H₂S and C₂H₅OH are both higher than those of the cubic structures, which may find potential industrial applications in detecting gases.