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. 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:

It can also be formed from oxygen difluoride and hydrogen sulfide:^{[citation needed]}