Spinel MgFe2O4 Was synthesized at 1373K from oxides MgO and Fe2O3 using Silica-tube technique with intermediate grinding. The product is homogenous and fine grained with the inversion parameter of 0.75. Calorimetric measurements indicate the second-order phase transition at 597 K. The technique of the synthesis is applicable to the spinels of metals with variable valency, for it prevents the escape of oxygen at long heating. (C) 2004 Elsevier B.V. All rights reserved.