A Zn-Sn precursor with cubic-shaped particles was successfully prepared by a simple coprecipitation method to obtain Zn-Sn mixed oxide (ZTO) catalysts. The resulting ZTO catalyst maintained the cubic shape even after calcination at 900 degrees C. The catalytic activity for the cyanosilylation of benzaldehyde with trimethylsilyl cyanide increased with increasing calcination temperature, and reached the maximum value at 600 degrees C. The ZTO catalyst calcined at 600 degrees C exhibited higher catalytic activity than the other solid acid catalysts, SiO2-Al2O3 and Amberlyst 15 DRY.