The novel ethyl derivative of 3-hydroxy-2-quinoxalinecarboxylic acid has been synthesized for the first time, characterized by FT-IR spectroscopy and single-crystal X-Ray diffraction. The crystal packing is achieved by inter-molecular C-H center dot center dot center dot N, C-H center dot center dot center dot O and N-H center dot center dot center dot O type hydrogen bonds, which play an important role in the formation of the 3D supramolecular network of the title compound. The geometries and vibrational frequencies of the title compound in monomer and dimer forms were investigated by density functional theory calculations employing the B3LYP hybrid functional. The calculation results are in accordance with the experimental data. In addition, the theoretical electronic properties like natural bond orbital (NBO) charges and frontier molecular orbitals were presented.