In this study, copper nanoparticles (Cu NPs) were synthesized using a rapid, single step and completely green biosynthetic method by reduction of CuCl2 center dot 2H(2)O solution with aqueous extract of leaves of Otostegia persica containing fiavonoid and other phenolics as a main factor which acts as reducing agent and efficient stabilizer. UV-vis spectra gave surface plasmon resonance (SPR) at 560 nm. The Cu NPs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). A possible synthesis mechanism of Cu NPs was presented. In addition, we investigated the catalytic activity of Cu NPs for the one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles under mild reaction conditions with good to excellent yields. The catalyst could be easily recovered by centrifugation and reused at least five recycles with no significant decreases in the yields. (C) 2016 Elsevier Inc. All rights reserved.