Abstract: A process and a system allow producing sodium hydrosulfite crystals. A suspension containing sodium hydrosulfite is provided. The sodium hydrosulfite crystals are separated from a remainder of the suspension. The separated sodium hydrosulfite crystals are cooled to a stable temperature. The suspension may be obtained by raising a pH and lowering a temperature of a solution containing sodium hydrosulfite. A partial precipitation of the sodium hydrosulfite to form the crystals may be facilitated by addition of a nucleating agent to the suspension.