1,1-Difluoroethylene, also known as vinylidene fluoride, is a hydrofluoroolefin.

This colorless, flammable gas is a difluorinated derivative of ethylene.

Global production in 1999 was approximately 33,000 metric tons.

[3] It is primarily used in the production of fluoropolymers such as polyvinylidene fluoride and FKM.

1,1-Difluoroethylene can be prepared by elimination reaction from a 1,1,1-trihaloethane compound, for example, loss of hydrogen chloride from 1-chloro-1,1-difluoroethane:[5] or loss of hydrogen fluoride from 1,1,1-trifluoroethane:[6]