With the rapid development of dedicated fright corridors, semi-high speed railroads and upgradation of the existing railroad to higher speed limit, Indian railways need a huge amount of natural ballast material. However, towards sustainable development, steel slag has enormous potential to be used as railway ballast. An in-depth understanding of material characteristics of steel slag is imperative for its proper use as a ballast material. The present studies examine the suitability of steel slag as railway ballast material based on their physico-chemical and mechanical characteristics. The physical properties such as specific gravity, water absorption and particle size distribution have been determined. For the chemical characterization, X-ray diffraction and energy-dispersive X-ray spectroscopy have been carried out and found that steel slag is enriched in calcium oxide (CaO), iron oxide (FeO) and silica (SiO 2 ) along with a little amount of magnesia (MgO) and alumina (Al 2 O 3 ). Along with it, leaching of heavy metals such as Hg, Pb, As, Ba, Cd, Cr, Cu, Fe, Ni and Zn from it using acid digestion testing method has also been carried out. Mechanical properties such as resistance of steel slag aggregate against abrasion, impact and crushing action have been performed. In addition, the cyclic triaxial tests are performed to get a better insight into characteristics under a passing train wheels. Maximum deviator stress and angle of shearing resistance are determined from monotonic load tests, and resilient modulus, permanent axial strain and damping ratio are determined from cyclic load tests. Results show that physical and mechanical properties are within the standards prescribed by the major countries.