The vibrational-rotational energy levels of the hydrogen peroxide isotopomers H2O2, D2O2, HOOD, and (H2O2)-O-18 have been predicted by the variational method using a high-quality ab initio six-dimensional potential energy surface. The calculated energy levels are found to be in good agreement with available experimental data. The predicted spectroscopic constants for various isotopomers can be useful in a future analysis of the rotational-torsional spectra and experimental determination of the equilibrium structure of hydrogen peroxide.