[en] The reaction of ¹⁵O, produced in pure nitrogen by the ¹⁴N(d,n)¹⁵O reaction, with the graphite walls inserted inside the target chamber was systematically studied. The ¹⁵O reacts quantitatively with carbon to form [¹⁵O]CO and [¹⁵O]CO₂ at the graphite temperatures of over 200 C. The effects of the irradiation parameters such as beam current, wall temperature, graphite surface area, N₂ flow rate and target pressure on the distribution of ¹⁵O-reaction products were investigated. The results clearly show that the ¹⁵O first forms [¹⁵O]CO, which is then rapidly oxidized into [¹⁵O]CO₂ under intense radiation. The strong reduction of [¹⁵O]CO₂ on the walls, induced by the radiation, was also observed especially with a lower flow rate and higher beam current. The present approach can be applied to a new method for the production of no-carrier-added [¹⁵O]CO and [¹⁵O]CO₂. (orig.)