The single crystal of 1-amino-1-ethylamino-2, 2-dinitroethylene (AEFOX-7) was obtained. The crystal structure of AEFOX-7·H₂O is orthorhombic, space group Pna2(1)/m with crystal parameters of a=1.3692(3) nm, b=0.71240(16) nm, c=0.9024(2) nm, β=90°, V＝0.8802(4) nm³, Z＝4, μ＝0.133 mm^-1, F(000)＝408, D_c ＝1.465 g·cm^-3, R₁＝0.0306 and wR₂＝0.0855. Enthalpies of combustion of AEFOX-7, AMFOX-7 (1-amino-1-methylamino-2, 2-dinitroethylene) and FOX-7 at 298.15 K were determined, and the corresponding enthalpies of combustion were -(2347.83±4.84), -(1819.96±5.94) kJ·mol^-1and -(1159.77±1.30) kJ·mol^-1, respectively.