The reaction between fluorine and water can be represented as:

This is an example of a redox reaction as water is getting oxidized to oxygen, while fluorine is being reduced to fluoride ion. The oxidation numbers of various species can be represented as:

Fluorine is reduced from zero to (– 1) oxidation state. A decrease in oxidation state indicates the reduction of fluorine.
Water is oxidized from (– 2) to zero oxidation state. An increase in oxidation state indicates oxidation of water.