This chapter discusses isochronal recovery and annealing of the electrical resistivity behavior of Co (cobalt) after low temperature irradiation with e-- and fast neutrons. The annealing of DXS indicates that only small interstitials agglomerates are formed up to 300K. Only a small amount of annealing is observed after plastic deformation. Due to the phase transformation at T ≈ 688 K, there are no quenching results and no quantitative self-diffusion data for hcp Co. Stage I is observed by ΔQ and by MagR. Stage III has been shown to be dose dependent, and nearly complete annealing is observed for e--irradiated samples. There is no detailed information on stage V, however some damage seems to be left up to 500 K after n-irradiation. Annealing of low dose e--irradiated samples showed some "superannealing", that has been attributed to the redistribution of impurities. Properties of Frenkel defects (FD), self-interstitial atoms (SIA), and vacancies (V) in cobalt are tabulated.