The mechanism of evaporation of various metal oxides and the formation and evaporation of metal halides in the presence of chlorine-containing compounds have been studied by complex thermal analysis including atomic absorption measurement of the evolved species. Th e /PVC or Cerechlor 70 / retardation process in the case of the MoO3+ \halide donor and the ZnO+ PVC or Cerechlor 70 / halide donor system and that for A1203 -3H20 has been discussed.It is well known that antimony trioxide (Sb203) is the most frequently used flame retardant additive for polymers due to its numerous advantageous properties. It is applied in the presence of halogen-containing compounds such as PVC or chlorinated paraffin where a pronounced synergetic effect develops. This effect is attributed to the formation of antimony trihalides (SbX 3 where X = C1 or Br)The mechanism of evaporation of Sb203 and that of the formation and evaporation of SbX 3 were studied at different Sb/X mole ratios by means of complex thermal analysis (TA) and flame atomic absorption technique (AT). With the aid of these methods the temperature of SbC13 formation and its evaporation could be detected [3].Some attemps have been made recently to study the interaction of halogenated organic compounds with various metal oxides in order to replace Sb203 by other metal oxides.