Development of a computation fluid dynamics (CFD) model for a direct injection into the combustion chamber of the hydrogen-fuelled engine was presented. An integrated subroutine is developed to simulate the hydrogen-injection process in a gaseous state. The reacting flow and accompanied physical phenomena were numerically analyzed utilizing the KIVA code based on multidimensional fluid mechanic theory. The developed model was successfully executed for low and high engine speed under lean mixture condition. Patterns of the flow field combined with the history of hydrogen concentration inside the combustion chamber during the injection phase were utilized for evaluating the performance of the hydrogen injection process. The identical distribution for the hydrogen concentration was observed. As well, the vectors of the flow field seem to have a bigger size and coarser distribution in case of the high engine speed (5000 rpm), especially near to the piston face. The developed model can be extended for further optimization process. © 2012 Praise Worthy Prize S.r.l. - All rights reserved.