The existence of the element fluorine had been well known for many years, but all attempts to isolate it had failed, and some experimenters had died in the attempt.[citation needed.
Moissan eventually succeeded in preparing fluorine in 1886 by the electrolysis of a solution of potassium hydrogen difluoride (KHF2) in liquid hydrogen fluoride (HF). The mixture was needed because hydrogen fluoride is a nonconductor. The device was built with platinum/iridium electrodes in a platinum holder and the apparatus was cooled to −50°C.
The result was the complete isolation of the hydrogen produced at the negative electrode from the fluorine produced at the positive one. This is essentially still the way fluorine is produced today. For this achievement, he was awarded the Nobel Prize in 1906. Late in his life, the government of France named him a Commandeur de la Legion d'honneur.
According to wikipedia