The structures, interaction energies, vibrational analysis, and electronic properties for different urea-hydrogen peroxide (UHP) 1:1 complexes have been studied. Density functional theory (DFT) using the B3LYP hybrid exchange-correlation functional was employed to characterize five new cyclic structures in addition to the experimental one. The basis sets used were Dunning's correlation consistent cc-pVDZ and Pople's 6-31G(2d,p) ones. Ab initio MP2(full)/6-31G(2d,p)//MP2(full)/6-31G(2d,p) calculations were performed to verify the appropriateness of the DFT methods for hydrogen-bonding systems. The basis set superposition error has been eliminated by using the full counterpoise correction method. The Bader analyses were also applied to investigate the hydrogen-bonding electronic properties.