We have prepared (Ca1−x−yMxBiy)3Co4Oz (M = Mg, Sr, and Ba) thin films by a combinatorial approach using a solution process. In the systems of (Ca1−x−yMxBiy)3Co4Oz (M = Mg, Sr, and Ba), solid solution range was determined to be × < 0.8 (M = Sr, y = 0), x < 1.0 (M = Mg, y = 0), x = 0.0 (M = Ba, y = 0), and x < 0.4 (M = Bi, x = 0). No solid solution range was obtained for the substitution of Ba for Ca site. The in-plane compressive stress in the CoO2 sublattice is controllable by the cation substitution for Ca in the (Ca2CoO3) sublattice. With increasing in-plane stress, the magnitude of thermoelectric power and resistivity increased.