Research has been carried out with the aim of studying the formation of functional groups of a composite of silver silica (Ag/SiO2) based on rice husk silica and silver nitrate (AgNO3) as a precursor using the sol-gel method. Variations in the concentration of AgNO3 used were 0,3M; 0,5M; and 0,7 M with a thermal temperature of 850 °C. The results of Fourier transform infrared spectroscopy (FTIR) showed the formation of Si-O-Si, Si-O, and O-N-O functional groups which were the result of AgNO3 residue indicating the presence of Ag.