Regular oscillations in the current are predicted in low‐pressure, planar discharges under certain conditions in electronegative gas mixtures in which the attachment rate coefficient is large at low values ofE/P, the ratio of the electric‐field strength to the gas pressure. The frequency of the oscillations is about 10 kHz, and depending on the conditions of pressure, gap spacing, and applied voltage, the current wave form varies from a near‐sinusoidal shape to regularly repeating and well‐separated spikes with a peak current density on the order of or less than 1 mA/cm2. The instability which gives rise to these oscillations is due to attachment, and the oscillations result from alternate phases of space charge buildup and decay. Thus, the current oscillations predicted here in planar discharges are analogous to Trichel pulses, periodic current spikes which are observed in negative point‐plane corona discharges in electronegative gases. ©1995 American Institute of Physics.