This monograph covers importance of heterocyclic compounds in daily life and their synthesis using green chemistry approach. The description involves synthesis of heterocycles such as tetrahydrobenzo[b]pyran, bis-indolylmethanes, pyranopyrazoles, pyrazolo[1, 2 -b]phthalazine-diones and (3, 5-Dimethyl -1H- pyrazol-4-yl)-phenyl-diazenes through one pot method of synthesis and further study of biological activities. Rigorous scrutiny of synthesized compounds for biological activity study has been carried out using standard and authentic cultures of bacteria and fungi. Some of the synthesized heterocycles exhibit potential antimicrobial activities.