The magnetic properties of three hexagonal perovskites—Ca 3 Co 2 O 6 , the 2H- and 12H-BaCoO 3− δ —have been studied by magnetization (M) measurements. In the latter, the isothermal magnetic field driven M(H) curves reveal M jumps for the lowest T(=2K), which are not observed in the 2H-BaCoO 3 1D compound. The comparison to the M steps found in Ca 3 Co 2 O 6 points towards a different origin in the case of the 12H-BaCoO 3− δ perovskite. This suggests that the pinning of the domain walls in this ferromagnet is made by a narrow distribution of critical fields of the nucleation growth responsible for these very reproducible M jumps. A clear relationship to the 3D structural character of the 12H perovskite is also made.