The ability of a non-thermal plasma (NTP) and heterogeneous catalyst combination to achieve reaction yields that exceed the contributions of the individual components is well documented. Often reactions are explored at conditions at which background NTP yields are non-negligible. Disentangling the gain achieved by combining NTP and catalyst from the background contributions of NTP and catalyst alone, and inferring the origins of yield enhancements, are thus significant practical challenges. Here, we demonstrate NTP-catalytic nitrogen oxidation: