Chapter “Sintering of iron ores and concentrates” is focusing on the study of theoretical, thermodynamic and experimental results in the production of sinters from iron ores and concentrates. The authors of the chapter have long been interested with the production of sinter from iron ores and have recently also focused on the use of biomass as a substitute for a part of coke breeze in the production of iron sinter. Important characteristics of the chapter include the characteristics of iron ores and concentrates used to produce sinter including physico-chemical, mineralogical and metallurgical properties. Predicting the influence of the properties of iron ores and concentrates on the final quality of the sinter and on the production of pig iron is another part of the study. These properties are a key factor in achieving the highest possible agglomerate quality for pig iron production. The sintering process requires mathematical and physical modeling. For this reason, the authors created thermodynamic models of sintering including material-heat balance of sinter production. In the final part of chapter is the use of traditional and alternative carbonaceous fuels in the production of sinters, mainly in the context of replacement of coke breeze with biomass.