The title molecule (DMPH-H), C8H9N5O6, was investigated to provide comparison with 2, 2- diphenyl-1-picrylhydrazine, which unlike DMPH-H is readily oxidizable to form a well known stable free radical (DPPH). The structure shows essential differences in the configuration of the hydrazine-N atoms, the ortho-nitro group orientations and the crystal packing. The bond angles of the dimethylamino N atom [107.90 (13), 108.96 (12) and 112.21 (13)°] are ...