Evidence is provided, which shows that the remote NH functionality is crucial to the catalysis, without which there is no dehydrogenation, and suggests that formic acid plays a dual role, acting both as a hydride and a proton source and as a proton shuttle. The NH proton does not directly protonate the Ir–H hydride, nor does formic acid. Instead, a formic acid assisted-proton hopping may occur, resulting in proton transfer from the remote to the proximal nitrogen atom, whereupon protonation of the hydride and subsequent release of H2 takes place