The hydrogen-bonded complexes between C2H4 and HNO3, and their deuterated analogs, have been isolated and characterized in argon matrices. The concentration studies, matrix annealing, and UV irradiation effects prove formation of stable 1/1 pi-electron hydrogen-bonded complexes isolated in two trapping sites. Eight perturbed HNO3 vibrations and three perturbed C2H4 vibrations were identified for this complex. The spectra also indicate the existence of a less stable 1/1 ct-electron hydrogen-bonded complex for which one perturbed frequency due to the OH stretching mode was identified. Photochemistry of the complexes was also studied with the 266 nm laser Line and with a medium-pressure mercury lamp. The photolysis products of HNO3, OH and NO2 radicals, recombine in the matrix cage to form nitric acid, and peroxynitrous acid which are the main-reaction products. The new major product of photolysis of the C2H4-HNO3 complex is ethylene glycol nitrite formed in double-addition reaction of OH and NO2 radicals to the C-C bond of the ethylene molecule.