Catalyst have played an important role in industry such as energy, pharmaceutical and chemical manufac ture since it allows reactions to occur faster at lower temper ature. For years, transition metal complexes have b een studied intensively as catalyst. In this work, a modified a morphous silica has been studied as support materia l for cobalt(II) acetonitrile complex through direct and indirect gr afting methods. The immobilized materials were char acterized by FT-IR, Optic Microscopy, TG-DTA, SEM, and AAS. Furt hermore, UV-Vis spectrophotometer was also used to determine electronic absorption of the complexes. I n general, either direct or indirect grafting produ ced grafted material with low leaching grade having less than 1 0 %. Thermal stability of such complex grafted on t he modified silica was moderately high and can be applied until 130 o C. On the other side, based on UV-Vis spectrophotom eter the catalyst is better if employed in a water free system.