Thiophosphoryl fluoride is an inorganic molecular gas with formula PSF3 containing phosphorus, sulfur and fluorine.

[5][7] They prepared it by heating arsenic trifluoride and thiophosphoryl chloride together in a sealed glass tube to 150 °C.

The pure gas is completely absorbed by alkali solutions, producing the fluoride and a thiophosphate (PSO3−3), but stable against CaO.

[5] Reaction with neutral water is slow: Nevertheless, dissociation constants for related acids suggest that the phosphorus atom is at least as electrophilic as in phosphoryl fluoride.

[5] In air, PSF3 burns spontaneously with a greyish green flame, producing solid white fumes containing SO2 and P2O5.

[10][14] For example, with cesium fluoride:[15] Thus PSF3 combines with dimethylamine in solution to produce dimethylaminothiophosphoryl difluoride (H3C−)2N−P(=S)F2 and difluorophosphate and hexafluorophosphate ions:[10][16] PSF3 reacts with four times its volume of ammonia gas producing ammonium fluoride and a mystery product, possibly P(NH2)2SF.

[5] PSF3 does not react with ether, benzene, carbon disulfide, or pure sulfuric acid.

It has a Trouton constant (entropy of vaporization at the boiling point of the liquid) of 24.4, and a heat of evaporation of 9530 cal/mole.

It has a non-uniform distribution of positive and negative charge which gives it a dipole moment.