ZnSn(OH)(6) polycrystalline cubic particles with perovskite structure were synthesized by hydrothermal method with the presence of hexamethylene tetramine (HMTA) as organic functional reagent. Experiments reveal that HMTA can adjust the nucleation rate and growth rate of ZnSn(OH)(6) in the synthesizing system. When the content of HMTA is 4.6 wt%, the nucleation rate of ZnSn(OH)(6) is more than its growth rate. As a result, the particle size of ZnSn(OH)(6) cube obtained at this condition is smallest whereas its average crystalline size is biggest compared with other samples. After dehydration of ZnSn(OH)(6) precursor at high temperature, the above particle and crystalline size characteristics make the resulting amorphous ZnSnO3 display an excellent UV sensitivity and gas-sensing property at room temperature comparable to other UV photo- and gas-sensitive materials. Possible reason of its comprehensive properties were discussed. Moreover, if Zn in the ZnSnO3 molecule is partly replaced by Mg with the formation of Zn(0.9)Mg(0.1)SnoO(3), its UV photoelectric properties can be further enhanced. The ratio of I-light/I-dark of the Zn0.9Mg0.1SnO3 sample is > 10(4), and its response and recovery time are about 4 s and 9 s, respectively.