Dihydrazinium, hydrazinium, hydrazinium ammonium, and ammonium salts of ethylenediaminetetraacetic acid (H4edta) such as (N2H5)2H2edta, N2H6H2edta, N2H5NH4H2edta and (NH4)2H2edta have been prepared and characterized by elemental analyses, hydrazine analysis, conductivity measurements, and infrared spectra. The thermal degradation studies reveal that these compounds undergo complete and multi step decomposition with or without melting. The IR spectra show that in all the cases the acidic protons are attached to the tertiary nitrogen atoms of edta and all the salts exist as zwitterions. The X-ray single-crystal data and the corresponding ORTEP diagram of the dihydrazinium and hydrazonium salts clearly support and confirm the data. Hydrazinium hydrogenethylenediaminetetraacetato aquo cadmium(II) monohydrate, N2H5[Cd(Hedta)(H2O)].H2O, has been synthesized and structurally characterized. The crystal belongs to orthorhombic crystal system and the space group Pbca. The crystal data are the following: a = 9.423 Å, b = 4.406 Å, c = 23.838 Å, α = β = γ = 90°, V = 3236 Å3, Z = 8, Dc = 1.932 Mg/m3, μ = 1.412 mm−1, F(000) = 1904, the final R = 0.0190, and wR = 0.0562 for 3707 observed reflection with I›2σ(I).