Abstract: This paper presents results obtained during experiment research on the insulation recovery of the rep-rate gas spark gap. Insulation recovery information has generally been obtained using a two –pulse technique while the nanoseconds pulse breaks down the gap. First, under static conditions (unblown), hydrogen gas allows an order –of –magnitude improvement in the recovery of an unblow spark gap. Under dynamic conditions (gas flow), gas between the electrodes allow a significant improvement in the switch recovery.