Various studies have shown that surface properties and wear resistance of gray cast iron can be improved by addition of alloying elements or reinforcing particles to the whole bulk of a component. However, these methods may have adverse effects on other properties, such as toughness. The purpose of this study was to investigate the possibility of improving the surface properties of gray cast iron by in situ surface alloying and compositing by in-situ addition of aluminum to the casting surface during casting. For this purpose, double cavity molds were prepared by sodium silicate bonded silica sand method where 5 mm diameter aluminum rods were planted on its lower side. Molds were then poured by molten hypoeutectic gray cast iron with a carbon equivalent of 4.08 at temperature of 1410 °C. Microstructural and mechanical properties of the specimens were then determined using optical and scanning electron microscopy, EDS, XRD, micro and macro hardness, abrasion and roughness tests. The results showed that despite the much lower melting point of aluminum than the casting temperature, some of the aluminum rods retained their appearances at the bottom of the mold and only in areas limited to the dimensions of the aluminum rods different structures from the gray cast iron was formed. Microstructural studies revealed the formation of fine and coarse-grained inter-metallic particles, mainly showing Al 2 Fe characteristics due to the diffusion of iron and silicon in this area. Also, in the cast iron field, by approaching the areas affected by the presence of aluminum, the coarse-grained A-type graphite