Disulfur difluoride is an inorganic compound with the chemical formula S2F2.

Disulfur difluoride has a chain structure F−S−S−F.

This structure is referred to as gauche, and is similar to H2O2.

There is a branched isomer of disulfur difluoride, thiothionyl fluoride, with the structure S=SF2.

Silver(II) fluoride can fluorinate sulfur in a strictly dry container at 125 °C (257 °F; 398 K), and the reaction produces FS−SF:[2] Disulfur difluoride undergoes intramolecular rearrangement in the presence of fluorides of alkali metals, yielding the isomer S=SF2:[3]