We report the synthesis and thermoelectric properties of high valence metal-doped [Ca2Co1-x
O3-δ]0.62CoO2 (M = Re, Mo or Nb) compounds. Approximately 10% M-doping for Co sites in block layer was found to be effective for dramatic suppression of oxygen nonstoichiometries. Seebeck coefficients were systematically enhanced with M-doping levels (x), and however, electrical resistivities also increased with x for conventionally sintered bulk samples. On the other hand, magnetic alignment and/or densification were remarkably effective for reduction of the resistivity. In the case of Mo-doped (x = 0.1) sample, a highly c-axis aligned and densified sample showed 1–3 times larger power factor at 1100K (5.3 μ WK−2cm−1) than the non-doped one. Moreover, these high valence metal doped Ca349 compounds exhibited the oxygen nonstoichiometry suppressed dramatically.