Abstract: A cross-linkable fluorine-containing elastomer composition comprising a fluorine-containing elastomer containing at least one of iodine and bromine in the molecule, an organic peroxide having a peroxy group --O--O--C(CH.sub.3).sub.2 R, where R is a lower alkyl group, in the molecule and an activation energy of not more than 34.0 Kcal/mole and another organic peroxide having the same peroxy group as defined above in the molecule and an activation energy of less than 34.0 Kcal/mole as cross-linking agents for the elastomer has less generation of CH.sub.3 I or CH.sub.3 Br at the decomposition of the organic peroxides without any substantial decrease in the compression set of the volcanization products.

Abstract: A peroxide-vulcanizable, fluorine-containing elastomer having distinguished processability, vulcanization characteristics and physical properties of vulcanized products can be obtained by polymerization of fluorine-containing olefins having 2 to 8 carbon atoms in the presence of an iodine and bromine-containing compound represented by the general formula RBr.sub.n Im, where R represents a fluorohydrocarbon group, a chlorofluorohydrocarbon group, a chlorohydrocarbon group or a hydrocarbon group, and n and m are integers of 1 and 2.