Dielectric barrier discharges (DBD) energised by voltage impulses with the rise rate of 300 V/ns and 500 V/ns have been investigated in the present work. A planar DBD reactor with a 0.5 mm gap distance was designed and developed. Experiment was carried out in oxygen at 0.02 bar gauge and ambient temperature of 20 . The reduced electric field (E/N) in the discharge gap under impulse voltages with the two different rise rates was measured. A photomultiplier (PMT) was employed to detect the emitted light when discharges took place. The total current through the reactor was measured and the impulsive discharge current inside the discharge gap was calculated with the help of a one-dimensional DBD electrical model. The charge transferred through the gap during the discharge under both rise rates was also calculated. Results show that impulse voltages with the rise rate of 500 V/ns can provide E/N of 683 Td in the discharge gap, and 546 Td can be achieved with the rise rate of 300 V/ns. The charge transferred under the rise rate of 500 V/ns was ~213 nC, 2.1 times higher than the ~101 nC transferred with the rise rate of 300 V/ns.