Ab initio SCF and Møller–Plesset correlation correction methods employing both 6-311G* and aug-cc-pVDZ basis sets have been applied to the optimizations of H 2 O 2 (H 2 O) n clusters with n=1–3. The binding energies have been corrected for the basis set superposition error (BSSE). An optimized stable cluster with a cyclic structure has been obtained for each degree of polymerization. The corrected binding energies of the stable dimer, trimer and tetramer are predicted to be −26.14, −54.51 and −98.68kJ/mol, respectively, at the MP4/aug-cc-pVDZ//MP2/aug-cc-pVDZ level. Binding energy for the dimer is in good agreement with that estimated from the experimental frequency shifts. The proportion of correlated interaction energies to their total interaction energies for all clusters is at least 36.3 percent, and the BSSE for ΔE(MP2) is at least 5.5kJ/mol. Hydrogen bond is dominant in all clusters. There exist cooperative effects in the cyclic trimer and tetramer. Vibrational modes associated with the peroxide O–H rocking modes exhibit large blue shifts as compared to that of H 2 O 2 , whereas those assigned to the stretching of OH, which is bound by H 2 O, exhibit very large red shifts with large intensities as the results of large dipole moment changes. Thermodynamic properties of water–hydrogen peroxide clusters at different temperatures have been calculated on the basis of vibrational analyses. The change of the Gibbs free energies for the aggregation from monomer to the dimer, trimer and tetramer are predicted to be 10.98, 20.24 and 17.30kJ/mol, respectively, at 1atm and 298.15K.