Tetrafluoro- and tetrachloro-4-pyridylnitrenes are formed on matrix photolysis of the corresponding azides and are found to be highly photostable in low-temperature matrices in contrast to nonhalogenated 4-pyridylnitrene. Matrix photolysis of 3,5-dichloro- or 3-chloro-5-cyano-2,4,6-triazidopyridines leads in rapid succession to mono-, di-, and trinitrenopyridines. The corresponding 3,5-dicyano-2,4,6-triazidopyridine does not produce an identifiable trinitrene. All the above species were identified by evaluation of the temporal evolution of the Ar matrix IR spectra and excellent agreement with DFT-calculated data.