Abstract.The behavior of two chemical modifiers based on platinum and tungsten, is studied in the two parts of this work. At first, the chemical and morphological alterations of these during pyrolysis and atomization stages in electrothermal atomic absorption spectrometry are studied. The compounds were H2PtCl6 and Na2WO4. A cylindrical graphite tube was used, and fixed shaped rectangular graphite plates were put inside as platforms to prepare the specimens. The crystalline formations on the platforms were studied by scanning electron microscopy and the energy dispersive X-ray spectra allowed the estimation of the chemical composition changes of the modifiers and the graphite surface. According to the spectra and the images obtained, both modifiers where found to change their crystalline form at temperatures between 5001250C. Severe corrosion of the graphite surface was observed in case of H2PtCl6 at temperature higher than 750C, while minor damages were observed in case of Na2WO4. In the second part of this work, the efficiency of these modifiers was tested for maximum loss-free pyrolysis temperature and atomization of lead by electrothermal atomic absorption spectrometry. The optimum results, concerning these parameters, obtained for medium concentration of the modifiers. The effect of each modifier on the atomization signal is discussed, and the optimum concentration of each one is estimated.