This master thesis presents a predictive physics-based zero-dimensional combustion model for Diesel premixed combustion. The main purpose driving the development of the presented combustion model has been its application for simulation of engine transient operation, in premixed combustion mode. During transient operation, pressure, temperature and gas composition in the cylinder are slightly different from the optimally designed steady-state values, because of their slow dynamics. These deviations could result in a combustion process producing high noise and pollutant emissions or even misfire; thus, they must be compensated by means of fast regulating parameters, such as injection timings and rail pressure, to achieve the desired combustion behavior.