# In a hydrogen fuel cell stack, is pure oxygen required?

I have been researching making a hydrogen fuel cell to produce electricity. However, since pure oxygen is expensive, is pure oxygen needed for the dry fuel cell stack or can the oxygen in the air be used.

• You will have to clean the air supply, dry the air supply, and have to deal with the low $\ce{O_2}$ concentration of normal air. – J. Ari May 22 '17 at 18:15
• Clean air, without sulfur compounds or other chemicals that "poison" the catalyst, should be sufficient. – DrMoishe Pippik May 26 '17 at 22:48