Proton-coupled electron transfer (PCET) is a reaction mechanism that is thought to be common in redox reactions. It involves the concerted transfer of an electron and proton to or from a substrate.

In PCET, the proton and the electron start from different orbitals and are transferred to different orbitals. They transfer in a concerted elementary step. PCET contrast to step-wise mechanisms in which the electron and proton are transferred sequentially.