A process for manufacturing hydrogen peroxide by an anthraquinone autoxidation process (AO-process) comprising two alternate essential steps of: (a) hydrogenation of a working solution in a hydrogenation unit in the presence of a catalyst, wherein the working solution contains at least one alkylanthraquinone dissolved in at least one organic solvent, to obtain at least one corresponding alkylanthrahydroquinone compound; and (b) oxidation of the at least one alkylanthrahydroquinone compound to obtain hydrogen peroxide in an oxidation unit; and further comprising step (c): extracting the hydrogen peroxide formed in the oxidation step in an extraction unit, wherein the hydrogenation, oxidation and extraction steps are performed in an reactor system which is designed as a compact modular system of a hydrogenation, an oxidation and an extraction unit, and wherein the reactor system is configured to operate without a reversion (regeneration) unit for continuous reversion of the working solution as a small to medium scale AO-process with a production capacity of hydrogen peroxide of up to 20 kilo tons per year, wherein the working solution and/or the catalyst are replaced and/or treated for regeneration or reactivation only intermittently or periodically, e.g., with a low frequency.