Plasma technology provides a sustainable, fossil-free method for N 2 fixation, i.e., the conversion of inert atmospheric N 2 into valuable substances, such as NO x or ammonia. In this work, we present a novel gliding arc plasmatron at atmospheric pressure for NO x production at different N 2 /O 2 gas feed ratios, offering a promising NO x yield of 1.5% with an energy cost of 3.6 MJ/mol NO x produced. To explain the underlying mechanisms, we present a chemical kinetics model, validated by experiments, which provides insight into the NO x formation pathways and into the ambivalent role of the vibrational kinetics. This allows us to pinpoint the factors limiting the yield and energy cost, which can help to further improve the process.