The production of the portland cement represents complicated technological process in which raw material, limestone and clay are fundementally changed and transformed by thermic treatment, producing cement clinker that after mixing with gypsum represents the final product – the portland cement. Clinker as the essential component of the Portland cement, is made by burning raw meal that containes oxides of calcium, silicon, aluminum and iron. By sintering at about 1450 o C, clinker minerals form that the final performance of cement depends, like hardness, thermal hydration, chemical resistance, durability and so on. In Portland cement clinker, four principal minerals are formed and that: tricalcium silicate (C 3 S), dicalcium silicate (C 2 S), tricalcium aluminate (C 3 A) and tetracalcium alumo- ferrite (C 4 AF). The production of Portland cement, starting at the quarry to the final product, must be under constant supervise and control. In the experimental part of the work, the raw material is prepared on semi industrial mill, and is analysed by laser diffraction apply to determine distribution and size of particles in the prepared mixture. The contribution of corrective components is determined by elemental analysis with the XRF method application. The final product – the portland cement clinker, is analized by use of the X-Ray Diffraction method (XRD), Thermogravimetry/Differential Thermogravimetry – Differential Thermal Analaysis (TG/DTG-DTA), and by optical microscopy in the darkfield. The results of the measurments aquired by different instrumental methods on the produced clinker show that conditions in the furnace are adequate for the synthesis of clinker minerals. However, oscilations of the results on the different clinker samples, indicate the oscilations of the quality of clinker product.