Effect of nitrogen and oxygen ion implantation (80 keV) on thin polycrystalline cobalt wire have been studied on the basis ofresidual lossangleandmagneticafter-effect measurements from 300 K to 450 K , using an automated Maxwell bridge. On a strongly temperature-dependent residual loss angle curve, after oxygen ion implantation ( dose 1019 m-2), an additionalradiation maximum at 350 K occurs , which might be attributed to a relaxation effect due to a reorientational or migrational motion of interstitial atoms.