We investigated the thermal stability of exo-tetrahydrodicyclopentadiene (exo-THDCP, C10H16) in the absence and presence of 5,6,7,8-tetrafluoro-1,2,3,4-tetrahydroquinoxaline (TFQox), a new hydrogen donor (H donor). Conversion of exo-THDCP was slowed in the presence of TFQox but less effectively compared to its analogues, 1,2,3,4-tetrahydroquinoxaline (THQox) and 1,2,3,4-tetrahydroquinoline (THQ). We analyzed the H-donor effects on the thermal decomposition kinetics of exo-THDCP, which explains the relative effect of the H donors on the thermal stability improvement of exo-THDCP.