A process for the preparation of lactic acid includes: a) providing an aqueous medium comprising magnesium lactate; b) adding to the aqueous medium a monovalent base to form an aqueous medium comprising a water soluble monovalent lactate salt and a solid magnesium base; c) separating the magnesium base from the aqueous medium; d) adjusting the concentration of the monovalent lactate salt in the aqueous medium, e) subjecting the aqueous medium to water-splitting electrodialysis, to produce a first solution comprising monovalent base and a second solution comprising lactic acid and monovalent lactate salt, the electrodialysis being carried out to a partial conversion of 40 to 98 mole %; f) separating the second solution into lactic acid and a solution comprising the monovalent lactate salt by vapour-liquid separation; g) recycling the solution of step f) comprising the monovalent lactate salt to step d).