A number of synthetic samples of sodium and potassium aluminosilicates with different compositions were prepared using an r.f.-induction furnace. Their characteristics as thermionic emission sources of alkali ions were studied and compared. Based on total emission current and its stability, and the purity of ion content, it was established that samples Na2O:Al2O3:2SiO2 and K2O:Al2O3:2SiO2 possess the best composition ratios to use as Na+ and K+ ion sources respectively.