Robust control of combustion phasing in Homogenous Charge Compression Ignition (HCCI) engines is a well-recognized challenge limiting the automotive industry for exploiting HCCI benefits in mass production vehicles. Real-time model-based control of combustion phasing is the key to tackle this daunting challenge. In this paper, a new control oriented model is developed for predicting HCCI combustion phasing over a range of engine operation. The model is validated against the experimental data from a single cylinder Ricardo engine. A model-based integral state feedback controller is designed to control HCCI combustion phasing by modulating the ratio of two Primary Reference Fuels (PRFs). The controller's performance is compared with a manually tuned proportional integral controller. The simulation results demonstrate that while both controllers have proper tracking performance, the model-based state feedback controller is more effective in rejecting the external physical disturbances and keeping the engine operation within the desirable range.