Granulated MgO-contg. fertilizers with high abrasion-and pressure-resistance are produced by mixing hot, dry technical KCl and/or K2SO4, recycled matl and, opt, hot kieserite with hot (ca 75-100 degrees C) moist (ca 15-25% H2O) langbeinite (K2SO4.2MgSO4) so that the overall moisture content of the mixt. is ca 3-10% and the temp. of the mixt. is ca 75-110 degrees C, granulating the mixt. with constant agitation, cooling the mixt. (with agitation) to 60 degrees C so that solidification occurs (accompanied by cleavage of the langbeinite and hydration of its MgSO4 component), sepg. off the granular matl., and recycling undersize matl.