In the present study, the thermo-physical properties of twenty-one submerged arc welding slags were analyzed using a rutile-basic system. The submerged arc welding slags were analysed using hot-disc and thermogravimetric techniques. Thermo-gravimetric analysis was performed from 25 °C to 900 °C to find the thermal stability and change in enthalpy of the slags. Multi-response optimization technique was used to derive the optimized slag formulations. Different regression models for thermo-physical properties were developed. Individual slag constituents have an antisynergistic effect on all the thermophysical properties except density. Binary and ternary slag mixture constituents significantly affect the thermophysical properties of submerged arc welding slag. © 2019, Springer Nature B.V.