Abstract: A process for producing magnesium oxide and/or hydrates thereof from predominantly magnesium or magnesium-calcium raw materials, and optionally producing calcium carbonate, whereby the raw material is roasted if necessary to form a mixture of magnesium oxide and calcium oxide. The calcium oxide is then dissolved from the mixture using an aqueous solution containing an organic amine and a salt of an organic amine with an acid capable of forming a soluble calcium salt with said organic amine. Separating the solution from the undissolved magnesium oxide and treating the solution with carbon dioxide will cause the dissolved calcium to be precipitated and calcium carbide.