A novel and ecofriendly procedure was developed for the synthesis of silver nanoparticles (AgNPs). The aqueous stem extract of Salvadora persica was used as reducing and capping agent. The formation of nanoparticles was observed at different temperatures and concentrations of the stem extract. Results indicated that at high temperature (120 degrees C) and concentration (30 mL), the reducing and stabilizing ability of the stem extract was declined. The synthesized AgNPs were highly dispersed, small sized (1-6 nm) and spherical in shape. The AgNPs were evaluated for photo degradation activity against methylene blue (MB) as an experimental substrate. Effect of various experimental conditions, such as catalyst amount, irradiation time and shape, size and dispersion of AgNPs were also investigated on the photo degradation of MB. The irradiation time experiment showed that photo degradation of MB was a rapid process and decomposed 96% in 80 min. The strong activities of AgNPs confirmed the significant application in water purification by converting hazardous materials into non-hazardous one. (C) 2015 Elsevier B.V. All rights reserved.