A study of irreversible reactions involving molecular nitrogen on Jupiter indicates that vertical motions are sufficiently rapid in the deep atmosphere to transport large amounts of N2 from the 900¿-1700¿K levels where it is stable up to the cold visible regions. Both homogeneous gas-phase and heterogeneous iron-catalyzed reactions between N2 and H2 were considered. We predict N2 mixing ratios of 0.6--3 ppmv if catalysis is effective and up to 10 ppmv if it is not. Thus, N2 may be the most abundant nonequilibrium species in Jupiter's troposphere and potentially detectable by the neutral mass spectrometer which will be on board the 1986 Galileo Entry Probe.