Ceramics based on the La2O3-SrO-TiO2-ZrO2-Fe2O3 system is of considerable interest for the development of the materials based on high-entropy oxides when their high-temperature endurance is required. However, limited information on its high-temperature behavior greatly limits its applications. In the present work, the potential of the geometric method for liquidus temperature calculation (GMLTC) in five-component oxide systems using data on the corresponding binary systems is verified for the first time with the example of the La2O3-SrO-TiO2-ZrO2-Fe2O3 system. The liquidus temperatures in the studied system calculated accordingly were experimentally confirmed by visual polythermal analysis within the limits not exceeding 10 % of the determined melting temperature. This allows us to recommend the proposed GMLTC approach for prediction of the position of liquidus curves in multicomponent oxide systems, which is particularly important for the calculations of liquidus temperatures of high-entropy oxides with unique physicochemical properties valuable for application at high temperatures up to 3000 K.