In the title compound, C6H7N3O3, the NNO2 group is twisted ca 59 degrees from the planar pyridine ring. The nitramino group is almost planar, with the N7 atom diverging 0.15 Angstrom from the C4-N8-C11 plane. The lone pair on N7 is included into the N-nitro group pi-electron system resulting in two independent sets of multicenter pi-orbitals. Significant anisotropy of the temperature dependence of thermal expansion is observed in the range 90-300 K.