Abstract: The current trend of modern industry is to use machineries rotating at high speed and carrying heavy rotor loads. In such applications hydrodynamic journal bearings are used. When a bearing operates at high speed, the heat generated due to large shearing rates in the lubricant film raises its temperature which lowers the viscosity of the lubricant and in turn affects the performance characteristics. Thermohydrodynamic (THD) analysis should therefore be carried out to obtain the realistic performance characteristics of the bearing. In the existing literature, several THD studies have been reported. Most of these analyses used two dimensional energy equation to find the temperature distribution in the fluid film by neglecting the temperature variation in the axial direction and two dimensional Reynolds equation was used to obtain pressure distribution in the lubricant flow by neglecting the pressure variation across the film thickness. In this paper CFD technique has been used to accurately predict the performance characteristics of a plain journal bearing. Three dimensional study has been done to predict pressure distribution along journal surface circumferentially as well as axially. Three dimensional energy equation is used to obtain the temperature distribution in the fluid film.