In this study, the corrosion behavior of refractory materials that were produced by incorporating ZrSiO 4 (zircon) at different ratios into MgO-FeAl 2 O 4 (hercynite) were investigated. The values of density and open porosity of those samples were also measured, and the corrosion behaviors of those materials produced were examined. After performing corrosion tests, the corrosion resistance of composite refractory materials were determined by measuring the penetration distances and spreading areas. The incorporation of ZrSiO 4 into MgO-FeAl 2 O 4 generally decreased the porosity of composite refractory materials, and consequently reduced the penetration distances and spreading area values of the corroded regions of refractories as well. In addition, the formation of new phases and the microstructural changes which occurred were determined by XRD measurements and SEM analyses. On the basis of microstructural characterization carried out in the interface of clinker-refractory, the following observations had been determined: i) Ca 2+ and Zr 4+ elements forming CaZrO 3 were located together in the same regions, ii) forsterite phase was formed due to the reaction between SiO 2 , which is released after dissociation of zircon as ZrO 2 and SiO 2 during sintering, and MgO, iii) the formation of new CaZrO 3 and forsterite (Mg 2 SiO 4 ) phases made a barrier effect against clinker, and iv) the amount of CaO decreased based on the EDX analysis made from clinker to refractory in a corroded region. The penetration of clinker to refractory showed a minimum level for the composition of MgO-5 wt.-% FeAl 2 O 4 -5 wt.-% ZrSiO 4 and an improvement by about 38 % as compared to MgO-5 wt.-% FeAl 2 O 4 . This improvement is associated with a long service life of MgO-FeAl 2 O 4 -ZrSiO 4 refractories for industrial applications.