[Li(NTO)(H2O)2] was prepared by mixing the aqueous solution of 3-nitro-1, 2, 4-triazol-5-one (NTO) and lithium hydroxide. The crystal structure of [Li(NTO)(H2O)2] was determined by single crystal diffraction analysis. The crystal is monoclinic, space group P21/n with crystal parameters of α=0.742 0(2)nm, b=0.344 9(1)nm, c=2.490 6(3)nm, β=94.89(1)α, Z=4, Dc=1.799g. cm 3, V=0.635nm3, μ=l.591cm-1, F(000)=392. The finaIR is 0.051. TheMNDOMOcalculation shows that the coordinate bonds of title compound possess certain extent of covalent character. 02 atom of NTO anion is bonded to Li atom; the nitro group will be lost first when NTO is decomposed.