Reactive collisions between CH 3 NNH 2 +NO 2 and CH 3 NHNH+NO 2 were observed via direct molecular dynamics simulations. The simulations, which are classical trajectories whose dynamics were dictated by forces derived from quantum mechanics-based calculations, were conducted: (1) to confirm the importance of reaction paths expected to play a role in the ignition and combustion of monomethylhydrazine/nitrogen tetroxide (MMH/NTO) and monomethylhydrazine/red fuming nitric acid (MMH/RFNA) systems, and (2) for their potential to identify unexpected mechanisms. A number of different H-atom abstraction paths were observed, with four isomeric (CH 4 N 2 ) products being formed: CH 3 NNH, CH 3 NHN, H 2 CNNH 2 , and CH 2 NHNH. All abstractions were barrierless, including those from the methyl group. Reaction exothermicities, which were characterized via QCISD/6-311+G(d,p)//MPWB1K/6-31+G(d,p) calculations, ranged from 2 to 36kcal/mol. The results suggest that finite rate chemical kinetics mechanisms for MMH/NTO and MMH/RFNA systems should include steps for the production and decomposition of CH 3 NHNH, H 2 CNNH 2 , CH 2 NHNH, and CH 3 NHN in addition to those for CH 3 NNH 2 and CH 3 NNH.