A novel electron-poor Eu6.5Gd0.5Ge6 compound adopts the Ca7Sn6-type structure (space group Pnma, Z = 4, a = 7.5943(5) angstrom, b = 22.905(1) angstrom, c = 8.3610(4) angstrom, and V = 1454.4(1) angstrom(3)). The compound can be seen as an intergrowth of the Gd5Si4-type (Pnma) R5Ge4 (R = rare earth) and FeB-type (Pnma) RGe compounds. The phase analysis suggests that the Eu7-xGdxGe6 series displays a narrow homogneity range of stabilizing the Ca7Sn6 structure at x approximate to 0.5. The structural results illustrate the structural rigidity of the (2)(proportional to)[R5X4] slabs (X = p-element) and a possibility for discovering new intermetallics by combining the(proportional to)(2)[R5X4] slabs with other symmetry-approximate building blocks. Electronic structure analysis suggests that the stability and composition of Eu6.5Gd0.5Ge6 represents a compromise between the valence electron concentration, bonding, and existence of the neighboring EuGe and (Eu,Gd)(5)Ge-4 phases.