The aim of this study is to develop a thermal modeling of a grease lubricated rolling bearing in order to analyze the heat evacuated through its solid parts and the lubricant. The system under consideration in this study is a clutch thrust bearing and more precisely a sealed single row angular contact ball bearing. To analyze heat transfer inside the bearing, two models have been developed using the thermal network method. These models have been compared to measurements performed on a specific test rig. As some heat transfers appear to be negligible, in the end a simplified model is proposed.