A free radical is a molecular species having an unpaired electron and it is a highly reactive entity and unstable. Free radicals are formed constantly in human system during metabolism or during the process of phagocytosis. Free radicals can also be generated from ionizing radiations, ozone, heavy metal poisoning, cigarette smoking and chronic alcohol intake. These free radicals are highly reactive and oxidise biomolecules leading to tissue injury and cell death. If these free radicals are removed by enzymes or nonenzymes involved in defense mechanism. To overcome this problem many antioxidants has been prepared in world. Here in order to determine the antioxidant properties, these compounds are evaluated. The compounds which are chalcones and chalcone based acetyl substituted and n-phenyl substituted pyrazolines such as (Ph1-Ph4 & Py1-Py4) were screened by using the process of DiPicryl Hydrazyl Radical (DPPH) model for antioxidant activity. Among the 16 compounds, Chalcone based acetyl and n-phenyl substituted pyrazolines are evaluated for antioxidant activity.