End product of denitrification process is

Denitrification is the microbial process of reducing nitrate and nitrite to gaseous forms of nitrogen. The preferred nitrogen electron acceptors in order of most to least thermodynamically favourable include nitrate, nitrite, nitric oxide and nitrous oxide finally resulting in the production of nitrogen gas completing the nitrogen cycle.
The end product of the denitrification process is N₂O and ultimately nitrogen gas, which is released back into the atmosphere.