Simple and eco-friendly method was developed for synthesis of silver nanoparticles (Ag NPs) via reduction of Ag+ by aqueous Grape leaves extract (GLE). Temperature induced synthesis of Ag NPs was performed and compared to photo-irradiation based method. Formation of Ag NPs was elucidated by both UV–vis spectroscopy and the change of color of the aqueous solution. The formation of Ag NPs is highly influenced by the reaction temperature. The higher the reaction temperature, the faster is the formation of Ag NPs. Phase composition, lattice strain and crystallinity of Ag NPs were analyzed by XRD. The prepared Ag NPs are stabilized by the presence of organic compounds originating from GLE which was proved by both XRD and FTIR analysis. TEM investigation of the synthesized Ag NPs showed that they are highly crystalline in nature and have sphere-like morphology with an average diameter of ~20 nm. The obtained Ag NPs showed efficient antibacterial activity against some Gram +ve and Gram –ve bacteria, particularly Staphylococcus aureus (+ve) and Pseudomonas aeruginosa (−ve).