The paper is focused at nitrogen oxides generation by transient spark (TS) in atmospheric pressure air. The TS is a DC-driven self-pulsing discharge with short duration (∼⃒10-100 ns) high current pulses (>1A), with the repetition frequency 1-10 kHz. Thanks to the short spark duration, highly reactive non-equilibrium plasma is generated, producing ∼⃒300 ppm of NOx per input energy density 100 J.l-1. Further optimization of NO/NO2 production to improve the biomedical/antimicrobial effects is possible by modifying the electric circuit generating the TS.