In the present study copper nanoparticles (CuNPs) were prepared using Syzygium aromaticum (clove) bud extract through simple and eco-friendly green route. The synthesized nanoparticles were subjected to structural, morphological, optical and antimicrobial studies. The high crystalline nature of CuNPs with a face centered cubic phase is evident from the X-ray diffraction (XRD) pattern. Morphological studies were used to study the shape and size of the synthesized nanoparticles. Energy dispersive spectroscopy (EDS) attests the high intense metallic peak of copper (Cu) and low intense peaks of carbon (C), oxygen (O), chlorine (Cl) and phosphorus (P) elements due to the capping action of biomolecules of bud extract in CuNPs formation. The zeta (ζ) potential of the CuNPs attests the stability of the nanoparticles. Ultraviolet-visible (UV–vis) absorption spectrum shows the characteristic absorption peak of CuNPs. Fourier transform infrared spectroscopy (FTIR) analysis shows the presence of different functional groups at various positions. The antimicrobial activity was investigated against the selected pathogens using bio-CuNPs. The positive test results of zone of inhibitions of 8 mm and 6 mm were attained against Bacillus spp. and Penicillium spp., respectively. © 2017 Elsevier GmbH