The paper presents the results of studies of argon-nitrogen plasma of a non-self-sustained low-pressure glow discharge with a hollow cathode by optical emission spectrometry. The plasma was generated in a mixture of Ar-N.sub.2 gases with an argon percentage from 0 to 100% at a total pressure of 1 Pa. The discharge current and voltage were maintained constant and amounted to 18 A and 165 V, respectively. A significant increase in the amount of Ar.sup.+ (up to 30%) at a nitrogen content of 10-25% was shown, which is associated with a shift in the reaction of charge exchange of nitrogen with argon towards the generation of argon ions. It was found that at a low partial pressure of nitrogen (approximately equal to 10%), a sharp increase in the content of atomic nitrogen is observed which is probably due to the dissociation of nitrogen molecules upon collisions with an excited argon atom. Keywords: low-pressure glow discharge, hollow cathode, plasma diagnostics, optical emission spectrometry, nitrogen dissociation, atomic nitrogen, argon plasma.