The crystal structures of the title compounds are reported. In all cases, the coordination sphere of the nickel atom comprises three bidentate ligands. In (1), [Ni(bpy)2(O2N)] NO3, <Ni-Né is 2•042 Å although there are small differences between those nitrogen atoms trans to the nitrite oxygen atoms and the other two. <Ni-O> is 2•12 Å. In (2), [Ni(bpy)3] NO2NO3, xH2O, and (3), [Ni(bpy)3]-SO4, 7•5H2O, a redetermination, Ni-N is shown to be c. 2.09 Å serious disorder is present among the non-cationic components of (2), precluding a definite assignment of stoichiometry.