He made the announcement today in Fredericton.
Coon says his 28 years of experience with the Conservation Council of New Brunswick positions him well to lead the Green party.
He says in that time he has travelled to every corner of the province working with citizens, educators and community groups.
Coon says the Greens under his leadership would remain opposed to shale gas development in the province.
He says he will step down from the Conservation Council until September's convention and only return to the group if his leadership bid is unsuccessful.
The Greens have no seats in the provincial legislature.