A process for the continuous preparation of hydroxylammonium salts by catalytic reduction of nitrogen monoxide by means of hydrogen in a dilute aqueous solution of mineral acid in a plurality of reaction stages connected in series comprises

• dividing the incoming stream of dilute aqueous solution of mineral acid into at least two substreams before it is fed into the plurality of reaction stages connected in series,
• feeding a first of these substreams to the first reaction stage,
• feeding a second of these substreams to a reaction stage other than the first, where the inflow of dilute aqueous solution of mineral acid into the plurality of reaction stages connected in series is controlled by means of the pH in this reaction stage other than the first.