Starting from an optimized synthesis of silylated phosphoric acid, OP(OSiMe), a borate salt bearing the [P(OSiMe)] cation was generated in the reaction of OP(OSiMe) with [MeSi-H-SiMe][B(CF)], isolated, and fully characterized. Analogously to the protonated species, phosphoric acid (HPO) reaction of OP(OSiMe) with a base led to the formation of the unknown [OP(OSiMe)] anion, which could be crystallized as potassium salt and structurally characterized, too. Both [P(OSiMe)] and [OP(OSiMe)] can be regarded as the formal autoprotolysis products of OP(OSiMe).