Rocket trajectories in a gravitational field between two terminals with specified velocities at each terminal are investigated with a view to total velocity increment required in initiating the rocket along the transfer path at the first terminal and in the attainment of the given final velocity at the final terminal. The equations are transformed for transfer between circular orbits and numerical results for Earth-Mars transfer are calculated. Finally particular cases of the above problem are discussed and Stark's results is drived therefrom