A series of CoNiAl composite oxide catalysts were prepared by calcining the CoNiAl hydrotalcite-like precursor at various temperatures and used in the catalytic hydrolysis of carbonyl sulfide (COS). The raw CoNiAl precursor and calcined products were characterized by various technologies. The catalyst calcined at 350 degrees C showed excellent activity and stability for COS hydrolysis at 50 degrees C and GHSV of 2000 h(-1) with temperature of water saturator of 25 degrees C. The CoNiAl precursor was decomposed at 350 degrees C to form NiO accompanying spinel phase and hydroxyl groups (OH-), which were active sites of the hydrolysis of COS. With lower calcination temperature, the precursor is incompletely decomposed to form mixed oxides, thereby decreasing the catalyst activity. Increasing the calcination temperature above 350 degrees C led to severe sintering of NiO and other active components, causing decrease in the number of active sites. The deactivation of catalysts was also investigated.