A modified hydrodynamic model for the analysis of submicron semiconductor devices is derived from the first four moments of a Boltzmann transport equation without invoking any phenomenological relations. Instead, the balance equations are truncated using a suitable ansatz for the electron distribution function in the fourth moment equation. Both conventional and modified hydrodynamic models are applied to ann+n−n+ballistic diode, and the results are compared. The new approach successfully suppresses spurious velocity overshoot without increasing the complexity of the model. Finally, the simulation of a two‐dimensional submicron metal‐oxide‐semiconductor field‐effect transistor by the modified hydrodynamic model is presented. ©1996 American Institute of Physics.