Twenty-six kinds of metal salts of 3-nitro-1,2,4-triazol-5-one were prepared and characterized by using modern analytical methods of element analysis, DSC measurement, TG analysis, ¹³C-NMR, XPS, electric conductivity, IR, and X-ray powder diffraction analysis. The results confirmed that these salts have a formula as M（NTO）_m·nH₂O.