We have studied the electron emission characteristics of the hydrogen-free diamondlike carbon (DLC) and conventional DLC films. The electron emission current of conventional DLC increases at first and then decreases continuously with bias stress time. The emission current of the hydrogen-free DLC, deposited by the layer-by-layer technique, increases at first and then stabilizes with increasing stress time. The resistivity of the hydrogen-free DLC decreases after long bias stress, and that appears to be due to the changes in the density of states in the gap of the hydrogen-free DLC. ©1997 American Institute of Physics.