This paper presents the experimental study on the hydrodynamic behavior of a jacket spar platform designed for 10 MLD (million liters per day) desalination plant in the water depth of 375 m with the pay load of 50×103 kN. The surge, heave and pitch natural periods from free decay tests are presented and validated with the numerical results obtained using NAOS (Non-linear Analysis of Offshore Structures) developed in IIT Madras. The jacket spar is modeled using sixty beam elements and each mooring lines by ten beam elements with axial prestress to model the pretension. The beam elements with axial prestress do not take any compressive load. The surge, heave and pitch response and mooring line tension of the jacket spar platform for three wave height range of 2.6m to 8.75m in the wave period range of 7.82s to19.00s are presented. The maximum surge of 0.5% of water depth, the maximum heave RAO of 0.1 and maximum pitch of 1.54° are within the operational limits. The maximum tension in mooring line is only 10% of breaking strength. Copyright © 2009 by ASME.