The corrosion of magnesia-chrome (MgO-Cr2O3) brick in molten MgO-Al2O3-SiO2-CaO-FetO slag has been characterized using a dynamic rotary slag corrosion testing for various test cycles at 1650 degrees C. The open porosity decreases from 15.3 to 4.0% for three cycles, then it gradually increases from 4.0 to 4.8% when the test is extended to nine cycles, in which the permeating depth of the slag maintains at about 20 mm. The XRD pattern of the permeated layer shows the presence of the MgO, MgCr2O4 and CaMgSiO4 phases. In the interior of the permeating layer cracks are formed and corrosion starts at the pores and cracks of MgO and decreases gradually. However, at 20-40 mm beneath the permeated layer edge, different shapes of MgO particles are found. (C) 2008 Elsevier B.V. All rights reserved.