Statistical characteristics of impulsive electric field (IEFD) associated with fast earthward ion flows in the inner central plasma sheet were studied by using electric field data obtained from the double-probe instrument on board the Geotail satellite. It is shown that the strongest electric field is produced in the region between XAGSM=-15 RE and -9 RE where the fast earthward flow is decelerated. The IEFDs are short-lived with a timescale of ~2 min on the average, compatible with the timescale of other signatures of substorm fine structures. This strong cross-tail electric field, coincident with the braking of the fast flow and correlated with the magnetic field dipolarization, has important implications for the particle acceleration in the near-Earth plasma sheet. ¿ 2000 American Geophysical Union