A simple method for the green synthesis of silver nanoparticles (AgNPs) using autoclave assisted gum extract of neem (Azadirachta indica) has been investigated for the first time. Silver nanoparticles were formed due to reduction of silver nitrate solution when mixed with the gum extract after autoclaving at 121 °C and 15 psi. The UV–vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 418 nm which is characteristic peak of silver nanoparticles. The functional biomolecules present in the gum extract and the interaction between the nanoparticles were identified by the Fourier transform infrared spectroscopy (FTIR) analysis. Average diameter of the synthesized nanoparticles was found to be