Abstract Pyrophosphate-linked coenzymes play essential roles in several biochemical systems. Symmetrical diadenosine-5′-pyrophosphate (Ap2A) has been synthesized from adenosine-5′-phosphate in virtually quantitative yield. The simple procedure is carried out in anhydrous pyridine using adenosine phosphoromorpholidate and adenosine monophosphate bis-(tri-n-butylammonium salt) as coupling reagents.