The rate constants and modes of reaction of N02+ and CzH50NOzN02+ with aromatic compounds and alkanes have been determined in a pulsed ion cyclotron resonance mass spectrometer. Both ions undergo competing charge transfer and substitution reactions (N02+ + M -MO+ + NO; CzH50NOzN02+ + M -MN02+ + CzH50N02) with aromatic molecules. In both cases, the probability that a collision results in charge transfer increases with increasing exothermicity of that process. The CzH50NOzN02+ ion does not undergo charge transfer with molecules having an ionization potential greater than about 212 kcal/mol(9.2 eV); this observation leads to an estimate of 13 kcal/mol for the binding energy between NOz+ and CzH50N02. The importance of the substitution reaction depends on the number of substituents on the aromatic ring and the molecular structure, and, in the case of C2H50-NOzN02' ions, on the energetics of the competing charge transfer process. Both N02+ and CzH50N02N02+ undergo hydride transfer reactions with alkanes. For both these ions, h (hydride transfer)/k(collision) increases with increasing exothermicity of reaction, but in both cases the rate constants of reaction are unusually low when compared with other hydride transfer reactions of comparable exothermicity which have been reported in the literature. This is interpreted as evidence that the attack on the alkane preferentially involves the nitrogen atom (where the charge is localized) rather than one of the oxygen atoms of NOz+.