Possible ionization effects on the analytical signal in mass spectrometry with a given high-temperature source are considered with the use of the multicomponent quasi-stationary thermodynamic model suggested previously for thermochemical processes in inductively coupled plasma. Changes in the electron concentration in the analytical zone due to the presence of matrix elements with different ionization potentials have been calculated, and groups of elements have been distinguished that essentially differ in the efficiency of influence. Three-dimensional plots of the electron concentration, the ratios between the partial pressures of matrix ions and electrons, and the degree of suppressing the ionization of analyte atoms with different ionization potentials have been constructed versus the temperature and the sodium concentration at various efficiencies of nebulization systems and various starting molar ratios of water vapor and argon. The main trends in ionization effects have been revealed. Model plasma compositions have been calculated for various added concentrations of interfering elements with different ionization potentials (Na, Mg, I, Br, Cl). With regard to mass discrimination in the mass analyzer, the possible degree of suppression of the signal of Co ions under these conditions have been calculated. On the basis of satisfactory agreement between experimental and theoretical results, a mode is recommended for the thermodynamic simulation of thermochemical processes in inductively coupled plasma. © 1998 MAEe Cyrillic signK Hayκa/Interperiodica Publishing.