The actual hydrogen consumption of a fuel cell stack varies with a fixed time delay under the step load change. For each individual stack, the delay time in the step-up load stage is generally shorter than in the step-down stage. Due to the hydrogen purge operation, transient overshoots take place intermittently after the actual hydrogen consumption reaches the steady state, and the duration and peak value of such overshoots are distributed approximately within a fixed range. Based on the performance investigation mentioned above, an improved dynamic model for hydrogen consumption of a fuel cell stack considering the effects of hydrogen purge operation is introduced in this paper. Compared with the previous model, the suggested model indicates a better agreement between test and simulation, especially in the working condition of hydrogen purge operation. (C) 2013 Elsevier Ltd. All rights reserved.