The article presents the results of studying the physical and chemical properties (temperature of the beginning, end and temperature range of softening, density) of the CaO-SiO2-Al2O3-Nb2O5-TiO2 oxide system with the addition of Fe2O3 and P2O5. Its chemical composition is comparable to the composition of domestic ore concentrates used to obtain complex ferroalloys with niobium. It has been established that all the studied oxide systems have low softening temperatures and are difficult to restore. The introduction of 24-29% Fe2O3 also leads to an increase in the softening temperature range to 420-470 °C. The pycnometric method determined the density of synthetic systems. The study of the density of oxide materials showed that the density of the studied samples is in the range from 3.32-3.91 g/cm3, and depends mainly on the content of iron oxides. © 2023 Author(s).