We have prepared polycrystalline Ca32xEuxCo4O9þd (x=0, 0.15, 0.3 and 0.45) samples using a sol-gel process followed by SPS sintering and investigated the Eu substitution effects on their high-temperature thermoelectric properties. With the Eu substitution, both the electrical resistivity and thermopower increase monotonously. This could be attributed to the decrease of hole concentrations by substitution of trivalent Eu3þ for divalent Ca2þ. The Eu substituted samples (x=0.15; x=0.3) have lower thermal conductivity than Ca3Co4O9þd due to their lower electronic and lattice thermal conductivity. The dimensionless figure of merit ZT reaches 0.3 at 1000 K for the sample of Ca2.7Eu0.3Co4O9+δ.