Abstract: In the present study, green synthesis of stable silver nanoparticles (Ag NPs) using callistemon viminalis extract as green-reducing and stabilizing agent was investigated. The Ag NPs were synthesized by heating a mixture of AgNO₃ and callistemon viminalis extract for different time intervals. The effects of parameters such as concentration of callistemon viminalis, reaction time and chitosan addition onto the physicochemical characteristics of the developed Ag NPs were evaluated. Formation of the Ag NPs was noted upon changing the solution color from pale yellow into brown and was confirmed by the appearance of surface plasmon resonance peaks at about 445 nm. The resulting Ag NPs were characterized by UV-vis spectrophotometry, X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy.