The hydrogen bonds formed between the hydroperoxyl radical and formamide, acetamide, and urea were characterized using geometric. energetic, along with the AIM analyses of the MP2 densities with the UMP2(full)/6-311G(d, p) method. Energetic analysis at G2MP2 level proved that the studied complexes are stable. The fundamental anharmonic OH vibrational frequencies calculated at this level of theory were 2840, 2749, and 2825 cm(-1) for the complexes of HO2 with formamide, acetamide and urea, respectively. The results allowed the characterization of the hydrogen bonds formed in the complexation of the amides with the hydroperoxyl radical. (C) 2004 Elsevier B.V. All rights reserved.