A numerical study has been carried out in differentially heated square cavities, which are formed by horizontal adiabatic walls and vertical isothermal walls. Three cases such as Natural convection in a cavity without any fins, with one fin and with two fins each placed equidistant from the center on the hot wall have been considered. Heat transfer by natural convection is studied by numerically solving equations of continuity, momentum and energy. A parametric study is carried out using the following parameters: Rayleigh number from 104 to 107, Prandtl number of 0.729, internal fin length of 0.10 m. A total of 24 cases have been considered and plotted using Fluent.