Plants are necessary for all life on Earth. As a critical part of the ecosystem, plants provide oxygen for organisms to survive. They are able to reduce the problem of pollution, by using carbon dioxide and releasing oxygen, an essential gas for all aerobic organisms. Also, there are many other processes that make them to survive in adverse conditions. One of such process is the role of enzyme in plant. In the present investigation activity of catalase enzyme was studied. Catalase an antioxidative enzyme minimizes cellular oxidative damage during stress condition in plants. In the present investigation activity of enzyme catalase was studied in Ficus religiosa, Ficus bengalensis and Ficus glomerata growing at various cross-roads of Ahmedabad city. From the study it was found that catalase activity was less in the leaves of plant growing in polluted area compared to those growing in low polluted area.