Hydrazinium metal citrate hydrates of compositions N2H5M(Hcit)H2O (M = Mn, Co, Ni or Zn; H(4)cit = citric acid) and (N2H5)(2)Ni(cit)4H(2)O and metal citrate hydrazinates of formulae M-3(Hcit)(2)6N(2)H(4) (M = Co, Ni, Zn or Cd] and Cu-2(cit)N(2)H(4)2H(2)O have been prepared and characterised by elemental analysis, IR spectroscopy, X-ray powder diffraction and thermal studies. IR absorption bands give evidence for the coordination of N2H5+ cation as a monodentate and neutral hydrazine as a bidentate bridging ligands in the complexes. Dehydration and dehydrazination followed by decomposition of the organic component produced the corresponding metal oxide as the final residue. The coordination of water has been substantiated by thermal analyses. The X-ray powder diffraction patterns show isomorphism among similar set of complexes.