Matrix isolation infrared spectroscopy has been combined with MP2/6-31+G(d,p) calculations to characterize the 1:1 hydrogen-bonded complex between H2O2 and (CH3)(2)O The O-H stretching mode was observed to red shift 234 cm(-1) upon hydrogen bond formation, while a 45 cm(-1) blue shift was noted for the O-O-H bending mode of the H2O2 subunit in the complex. These values compare well to the computed shifts of -293 and +20 cm(-1), respectively. The perturbations to the vibrational modes of the two subunits in the HOOH:O(CH3)(2) complex are substantially larger than the perturbations reported previously for the analogous HOH:O(CH3)(2) complex, suggesting that H2O2 is a better proton donor for hydrogen bonding than H2O. In contrast, band shifts in HOOH:O(CH3)(2) are much less than observed for FH:O(CH3)(2) and ClH:O(CH3)(2).