AbstractSome zinc chelates were prepared according to conventional methods, and were mixed with polypropylene in the presence and absence of a halogenated compound (Cereclor 70). The effect of these chelates on the flammability and thermal behaviour of polypropylene was studied by measuring the limiting oxygen index values and by the use of thermal analysis. This results showed that these chelates are ineffective in reducing the flammability of polypropylene but their effectiveness is enhanced to varying extents by the addition of Cereclor.