The present invention relates to a process for preparing an elastomeric
ethylene-hexafluoropropylene copolymer with excellent vulcanization
properties, which comprises emulsion polymerizing ethylene,
hexafluoropropylene and when in demand, a monomer copolymerizable
therewith in a aqueous medium at a low temperature of -20.degree. C. to
40.degree. C. using a radical polymerization initiator.
