This paper aims to investigate the effect of pitching amplitude, mean angle of attack and frequency of oscillation on the propulsive characteristics of a harmonically oscillating cambered airfoil at Reynolds number of . The flow field around the foil is analyzed to study the influence of the above parameters and to understand the reasons behind the positive thrust force generation. It is observed that the instantaneous force coefficients of the airfoil vary both qualitatively and quantitatively with respect to change in the above-mentioned parameters. A transition of wake from Karman vortex to reverse Karman vortex is observed. It is also observed that the formation and convection of the leading edge vortex over the airfoil surface has a strong impact on the drag-thrust transition. It is also noticed that the change in the location of the pitching axis has a significant influence over thrust force generation and propulsion efficiency of the airfoil.