Sulfur difluoride is an inorganic compound with the chemical formula SF2.

It can be generated by the reaction of sulfur dichloride and potassium fluoride or mercury(II) fluoride at low pressures: The F−S−F bond angle is 98°, and the length of S−F bond is 159 pm.

[1] The compound is highly unstable, dimerising to FSSF3.

This unsymmetrical isomer of S2F4 is proposed to arise via insertion of SF2 into the S−F bond of a second molecule SF2:[2] It can also be formed from oxygen difluoride and hydrogen sulfide:[citation needed]