Abstract: The invention discloses a method in the electrolytic production of alkali metal chlorate which is recovered by crystallization and separation of the crystals from a solution recycled to the electrolysis process. A given proportion of the crystals formed are separated and removed from the mother liquor after they have been in contact with the mother liquor for a shorter period of time than the remaining crystals, whereby they obtain a sulphate content which is higher than in the crystals that have been in contact with the mother liquor for a longer period of time.