Ag/SBA-15 catalysts have been prepared by means of in situ reduction methods using hexamethylenetetramine and formaldehyde as reducing agents, respectively, and characterized by N-2 adsorption/desorption, XRD, TEM and XPS. Presence of nanoparticles of silver in SBA-15 were confirmed by high angle X-ray diffraction data (peaks between 2 theta = 35-80A(o)) and XPS, and transmission electron microscopy confirmed the diameter of the nanoparticles. When hexamethylenetetramine was used as reducing agent, uniform Ag nanoparticles inside the channels were formed, and diameter of nanoparticles is found to be similar to 6.0 nm which is coincident with channel diameter of SBA-15. The catalysts were subjected to CO oxidation in a flow reactor at atmospheric pressure and temperatures up to 300 A degrees C. Studies revealed that catalysts prepared with different reducing agents strongly influence their catalytic performance in the CO oxidation, what prepared with hexamethylenetetramine as mild reducing reagent shows a certain low temperature catalytic activity.