Thermal and chemical (antibacterial) properties of Ag nanoparticles deposited on the surface of SiO₂ were studied to know the possibility of applying them as antibacterial materials. To prevent aggregation of Ag nanoparticles and increase their antibacterial abilities, hybrid structures of Ag−SiO₂ nanocomposites were synthesized by one-pot sol−gel method. The thermal behavior of Ag−SiO₂ nanocomposites were investigated with X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The antibacterial properties of Ag−SiO₂ nanocomposites were examined with minimum inhibitory concentration (MIC). The antibacterial property of the nanocomposites shows no significant change below Tammann temperature (e.g., 293 and 573 K); however, it was decreased upon increasing the temperature above Tammann temperature (673 − 1073 K) because of the growth of Ag nanoparticles deposited on the surface of SiO₂.