The study of process parameters in metals during heat treatment has been of considerable interest for some years but there has been relatively little work on process variables during the surface hardening process since controlling parameters in carburization is a complex problem. This work focuses on the parametric effects of the carburizing temperature and time on the mechanical properties of mild steel carburized with activated carbon, at 850, 900 and 950 °C, soaked at the carburizing temperature for 15 and 30 minutes, quenched in oil, tempered at 550 °C and held for 60 minutes. Sequel to carburization process, standard test samples were prepared from the as received specimen for tensile and impact tests. After carburization process, the test samples were subjected to the standard test and from the data obtained, ultimate tensile strength, engineering strain, impact strength, Youngs’ moduli were calculated. The case and core hardness of the carburized tempered samples were measured. Observation shows that the mechanical properties of mild steels were found to be strongly influenced by the process of carburization, carburizing temperature and soaking time at carburizing temperature. It was concluded that the optimum combination of mechanical properties is obtained at the carburizing temperature of 900°C followed by oil quenching and tempering at 550 °C.