ZnO Nanoparticles were simply synthesized by green biosynthesis method using ficus carica leaf extract. The structure of these nanoparticles was assigned using Fourier transform infrared spectroscopy (IR), Field emission-scanning electron microscopy (FE-SEM), and X-ray powder diffraction (XRD). The catalytic activity of these nanoparticles was studied for the synthesis of 4H-pyrans. A series of 4Hpyrans 3(a-l) were synthesized in good to high yields by reaction of corresponding α,α′-bis(substituted benzylidene) cycloalkanones and malononitrile in the presence of ZnO nanoparticles as a catalyst at 110 °C. This environmentally friendly method has some advantages such as high efficiency, use of available catalyst, solvent-free reaction conditions, and easy operation. The antibacterial activity of synthesized 4H-pyrans was also tested using Staphylococcus aureus and Escherichia coli bacterial strains.