One of the main goals in oxygen steelmaking process is to reduce the carbon concentration of the liquid iron effectively. It is understood that the majority of the carbon removal reaction occurs in the emulsion phase via the reaction between metal droplets and the slag phase. An improved understanding of this reaction and the factors controlling the overall rate should provide better control of the process and increase the productivity. In the literature, there is limited knowledge on how to relate the carbon removal rate within the droplets to the overall kinetics of the process under full scale operating conditions. A global model of oxygen steelmaking including the kinetics of scrap melting, flux dissolution, slag chemistry, temperature profile of the system, formation and residence of metal droplets in the emulsion, kinetics of decarburization reaction in different reaction zones has been developed. This paper will focus on the development of one sub-model on the decarburization reaction in the emulsion phase. This paper critically evaluates the current knowledge on the kinetics of decarburization reaction in the emulsion phase and discusses the repercussions of the new model for industrial practices. The model, in conjunction with the industrial data, suggests that approximately 70% of the decarburisation takes place in the emulsion phase during the main blow.