To provide a method for producing a monohalogenoheptafluorocyclopentane and 1H-heptafluorocyclopentene from 1H, 1H, 2H-heptafluorocyclopentane by-produced when producing the 1H-heptafluorocyclopentene by vapor-phase hydrogenation reaction or the like of chloroheptafluorocyclopentene on a noble metal catalyst.

The halogenoheptafluorocyclopentane is produced by bringing 1H, 1H, 2H-heptafluorocyclopentane into contact with a halogenation agent in the presence of a radical source. The halogenoheptafluorocyclopentane is brought into contact with an alkaline material to cause dehydrohalogenation reaction to provide the 1H-heptafluorocyclopentene.