[Sr(NTO)~2(H~2O)~4]~2.4H~2O was prepared by mixing an aqueous solution of 3-nitro-1, 2, 4-triazol-5-one and an excess of strontium carbonate. The single crystal structure has been determined on a four- circle X-ray diffractometer. The crystal is monoclinic, space group P2~1/c with crystal parameters of a=1.1034(1)nm, b=2.2742(2)nm, c=0. 63398(9)nm, β=101.798(13)ⅲ, V=1.5573(4)nm^3, D~c=1.936g.cm^-^3, Z=2, F(000)=912, μ=35.45cm^-^1, λ(MoKα)=0.071073nm. The final R is 0. 0344. From measurements of the enthalpy of solution in water of [Sr (NTO)~2(H~2O)~4]~2.4H~2O at 298.15K, the standard enthalpy of formation, lattice energy, lattice enthalpy and standard enthalpy of dehydration have been determined as -(2545.2±4.7), -2114, -2136 and 67.2kJ.mol^-^1, respectively.

Key words: NITRO COMPOUNDS, TRIADIMEFON, STRONTIUM COMPLEX, STRONTIUM CARBONATE, CRYSTAL STRUCTURE, THERMODYNAMIC PROPERTIES