In this study, the effect of thermocapillary and buoyancy driven flows in an open cavity filled with fluid is numerically examined. A physical configuration is encountered where a constant heating element at the bottom wall and cooled from the sidewalls while the top wall can be considered free surface. The length of the heat source is varied from 20 to 100% of t he total length of the bottom wall and remaining parts are adiabatic. The governing equations are discretized by finite volume method with power law scheme and solved numerically by SIMPLE algorithm. The effects of dimensionless heat source on flow and heat transfer are studied. The detailed flow pattern and heat transfer characteristics inside the cavity presented in the form of streamlines, isotherms, velocity profiles and average Nusselt number for different values of Grashof number and Marangoni number.