In this communication we report the synthesis and full structural characterization of the new phase Ba₈Co₂Mn₆ClO₂₂ formed of novel 8H-hexagonal perovskite blocks, a good example of the use of a multi-technique approach (combination of single crystal X-ray diffraction, micro-probe analysis and DFT calculations). Strikingly, the stabilization of original linear hexamers in the blocks is achieved by Mn/Co ordering in the octahedral and tetrahedral sites.