The trifluorooxonium cation is a hypothetical positively charged polyatomic ion with chemical formula OF+3.

The OF+3 cation was shown to be vibrationally stable at all levels of theory applied (HF, MP2, CCSD(T)).

However, the low-temperature reaction of F2, OF2 and AsF5 under UV irradiation, besides unreacted starting materials only yielded the dioxygenyl salt [O2]+[AsF6]−.

The oxidation of OF2 with KrF+ salts also failed to produce evidence for the title cation.

[1] The formation of the hypothetical salt [OF3]+[AsF6]− was calculated to be about thermoneutral, but slightly unfavorable with OF2(g) + F2(g) + AsF5(g) → [OF3]+[AsF6]−(s) = +10.5 kcal mol−1.