In this study, effects of increase in the coolant outlet temperature for the modular helium reactor (MHR) were studied. Therefore, the inlet temperature, flow rate and bypass flow fraction were modified to increase the outlet temperature. The simulations were carried out by using computational fluid dynamics software (ANSYS 12 FLUENT CFD code) as the steady-state condition in three dimensions with k-epsilon turbulence model and enhanced wall treatment. The simulated geometry was chosen as a unit cell. Four alternative operating conditions were proposed to MHR. The studied modifications substantially increased coolant outlet temperatures. In addition, they resulted in an increase of fuel centerline temperatures. In all of the cases considered, the maximum fuel temperature was obtained 1443 degrees C with a coolant inlet temperature of 491 degrees C and a coolant flow rate of 226 kg/s. Copyright (c) 2011 John Wiley & Sons, Ltd.