High density microprocessor packages are being deployed to achieve system performance improvements. However, the non-uniform heat dissipation characteristics of such packages has led to renewed interest in vapor chambers and heat pipes for heat spreading and transport. In this paper an approach to model the thermo-hydrodynamic performance of vapor chambers for cooling of microprocessor packages is presented. Model validation against data available in literature showed a very good agreement. The validated model was then used to study the performance sensitivity to vapor chamber design and operational parameters such as wick thickness, wick type, evaporator side heat input and condenser side heat extraction.