Abstract: A method and apparatus which enables a continuous horizontal casting of thin slabs operates on the principle of cooling the molten steel and the cooling mold from the top and bottom while the sides of the cooling mold are comprised of refractory materials which prevent solidification along the short sides of the mold. Consequently, during the initial phases of the solidification process the steel solidifies from the top and the bottom forming sheets of increasing thickness which squeeze and sandwich the molten liquid center. The process avoids formation of voids or other irregularities in the finished metal slabs and it results in a very low rejection rate of finished product. Particularly for application wherein thin metal slabs measuring less than 4 or 5 inches in thickness are produced, the upper side of the mold curves upwardly toward the inlet opening to prevent freezing of the molten metal at the opening.