Surface nanosecond dielectric barrier discharge in air has been studied in a pressure range 1–6 bar in coaxial geometry of electrodes for positive and negative polarity of high–voltage pulses. High-voltage pulses of 20–60 kV amplitude on the electrode, 20 ns duration, 0.5 ns rise time were used to initiate the discharge. ICCD images of the discharge development have been taken with 2 ns gate. It was found that at certain combinations of pressure and applied voltage the discharge becomes significantly filamentous