Abstract (PDF) Graphical Abstract: Silver nanoparticles colloids were prepared using the extract from the leaves of Vitex agnus-castus. The effect of temperature on the reduction of silver ions and on the growth of silver nanoparticles was followed by measuring the intensity of the surface plasmon resonance band in the UV spectra. It was found that fast reduction of silver ions occurs even at 40°C, while effective synthesis of silver nanoparticles requires elevated temperatures of 60-80°C.