The present work is aimed at CFD simulation and experimental study on frequency and amplitude dependency of heave damping of Spar hulls by forced oscillation along heave direction in calm water condition. Conventionally, the heave damping is obtained by free decay test of a scale model which gives damping only at the heave natural frequency, but the damping at frequencies other than natural frequency cannot be determined by this method. So the forced heave oscillation of Froude scaled Spar models were conducted in calm water condition over a range of frequencies and amplitudes of oscillation and the forces were measured along the heave direction to calculate added mass and damping from the equation of motion. The experimental investigations were performed on a classic Spar model with and without heave plate in a laboratory wave flume. The CFD simulations were carried out in a numerical tank using commercial CFD software. The measured heave force is compared with that obtained from CFD simulation. Further, the added mass and damping coefficient have been calculated by solving equation of motion from both experiment and simulation using the forces and heave motion as input. The amplitude and frequency dependency of heave added mass and heave damping for spar with and without heave plate are presented and discussed. © 2014: The Royal Institution of Naval Architects and IIT Madras.