Surface tensions of the parts of the NaF + AlF3 + AlPO4 and NaF + AlF3 + NaVO3 molten systems were investigated at four cryolite ratios (CR) [CR = n(NaF)/n(AlF3)] varied between 1.5 and 3 (1.5, 2, 2,5, and 3). The maximum bubble pressure method was used for the determination of this physicochemical property. In general, small additions of AlPO4 to the NaF-AlF3 molten system cause a decrease of the surface tension. By melting NaVO3 at low concentrations, new species with lower covalence of bonds occur compared with bonds of species presented in molten NaF-AlF3.