Abstract: A process for preparing a substantially pure aqueous solution of hydrogen peroxide is described. An impure hydrogen peroxide solution is vaporized in a vaporizer to form a vapor containing hydrogen peroxide and a concentrated hydrogen peroxide solution in equilibrium therewith. The solution also contains impurities. A substantially pure hydrogen peroxide solution is obtained by a partially condensing the vapor containing hydrogen peroxide. In addition to the solution, a residual vapor, in equilibrium with the solution and having a lower hydrogen peroxide concentration, can be condensed in a separate condenser. The concentration of the hydrogen peroxide solution obtained by the process can be regulated, for example, by regulating the condensation efficiency of the partial condensation.