Surface and interfacial phenomena play a significant role in refractory performance. For example, the wettability of the refractory material with slag, matte, and metal influences infiltration and interfacial reactions. Yet, very little fundamental information regarding the surface properties of refractory materials and slag is available. Thus, in the present work, the sessile drop technique incorporating a high temperature furnace equipped with X-ray fluoroscope was employed to investigate the surface and interfacial phenomena of fayalite-type slags on solid alumina at 1200°C. The iron to silica (Fe/SiO 2) ratios employed were 1.4 and 2.0, and the oxygen potentials used were log p 02=-11 and log p 02=-9 atmospheres. The contact angle between the fayalite-type slags and the alumina were determined to be relatively low, at about 16.9 to 19.6 degrees under the experimental conditions. The surface tension of fayalite slag (Fe/SiO 2=1.4) at an oxygen potential of log -11 was 0.298, which agreed with the work of previous researchers. The surface tension of the fayalite was observed to increase with time. The spinel FeAl 2O 4 was determined to be the product of the interfacial reaction, and 8.8 to 15.8 mass percent alumina was dissolved into the slag after 40 minutes.