An application of the Rist and Meysson model is presented to determine the efficiency of the reduction of iron oxides in blast furnaces, for the real-time detailed analysis as of historical periods of operation. As an example, the application is shown in the case of Blast Furnaces of Compañía Siderúrgica Huachipato S.A., a company of the CAP group in Chile and for No. 2 Blast Furnace of the Argentine company Ternium Siderar. The potential of the model is complemented with the analysis of variations in the main operational parameters and its influence on the unit fuel consumption.