A new homonuclear single-chain magnet self-assembles as a one-dimensional coordination network of defective dicubane {Co-4(II)} complexes linked by single Co-II ions with the assistance of azido and picolinate ligands. Dominating intrachain ferromagnetic interactions, intrinsic Ising-like Co-II anisotropy, and negligible interchain magnetic interactions lead to a thermally activated relaxation time of the magnetization below 8 K. Two thermally activated regimes above and below 3.5 K are observed with the following energy barriers: Delta(tau 1)/k(B) = 66 K (tau(0) = 3.7 x 10(-11) s) and Delta(tau 2)/k(B) 51 K (tau(0) = 2.3 x 10(-9) s), respectively. The difference between the two energy barriers of the relaxation time, 15 K, agrees well with the experimental energy, Delta(xi) to create a domain wall along the chain.