Many workers have paid more attention to eco-friendly mesoporous silica silver nanoparticles featuring smaller particle sizes to enhance their remarkable antimicrobial properties. A simple chemical method was developed for synthesize high valence silver nanoparticles immobilized on the mesoporoussilica nanomaterial, which showed strong antibacterial activity. Chemical reduction of silver ion has been regarded in the present work, and a reducing agent , such as hydrazine was used to promote the reduction of the silver ion – precursor. The average particle size of the synthesized mesoporous silica-silver nanoparticles (Ag/NH₂-KIT-6(x)) with different concentrations of Ag (3.2 and 7.1%) calculated from Scherrer's equation for (1 1 1)-plane were 8 and 6.5 nm respectively. The synthesized materials were characterized using X-Ray diffraction (XRD), FTIR spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM), which revealed the mesoporous silica nanoparticles. Antibacterial activities of mesoporous silver nanoparticles against Gram- negative Pseudomonas aeruginosa(ATCC 9027) and Gram-positive Staphylococcus aureus(ATCC 43300) were found to be increased with the increasing of Ag concentration in the Ag/NH₂-KIT-6(x). The maximum inhibition zone diameter when the concentration 7.1 % was used obtained against P. aeruginosaand S. aureuswith diameters of 32 and 30 mm respectively. The antimicrobial activity of mesoporousAg/NH₂-KIT-6(x) was evaluated also using the MIC&MBC tests. The surface structures of both the untreated and the treated bacterial cells were examined by the aid of TEM. The treated bacterial cells were significantly changed, and major damage was observed in the outer cell membrane. In conclusion the use of AgNPs as antibacterialagentwasfoundtobetoxicagainstpathogenicbacteriaandconsidered