1-Fluoro-4-hydroxy-1, 4-diazoniabicyclo [2.2. 2] octane bis (tetrafluoroborate), NFTh, is a electrophilic fluorinating that can be used to fluorinate aromatic rings, olefins, dienol acetates and enol ethers. When NFTh is reacted with an active methylene compound in the presence of ZnCl2, the corresponding monoor di-fluoro derivative can be isolated.