We report the production of gaseous hydronitrogen chemical species in a continuous-flow microwave plasma discharge excited in hydrazine (N2H4) gas in helium. Products were analyzed by Li+ ion attachment mass spectrometry. Plasma composition was investigated as a function of N2H4/He composition and microwave-induced power input. A variety of neutral and ionic products were formed and identified mass spectroinctrically. The mass spectral analysis revealed the presence of various cluster compounds of N2H4, H2O, and/or NH3 as well as their ionized species. These cluster compounds were formed by condensation reaction processes. In addition, the interesting neutral hydronitrogen species N3H5 and N4H6 were tentatively assigned. No species with these chemical formulas are listed in the NIST database. Formation of N3H5 and N4H6 may involve rearrangement reactions.