The effect of Cu doping on the structural, magnetic, electrical and thermal transport properties of Ca3Co2-XCuXO6 single crystals has been investigated systematically. Based on the analysis of the structural parameter and x-ray photoelectron spectroscopy spectra, the valence state of Cu is considered to be +2. All samples undergo a long-range spin density wave (SDW) transition at T-N and a glass-like magnetic transition at T-f with decreasing temperature. Both T-N and T-f decrease monotonously with increasing Cu-doping content. A series of magnetization steps can be observed in the M(H) curve of Ca3Co2O6, and the magnetization steps are sensitive to the sample cooling magnetic field and Cu doping content x. With the increase of x, the resistivity along c-axis decreases while the thermopower increases. As a result, the figure of merit (ZT) increases considerably and the room-temperature ZT value of the sample with x = 0.6 is nearly 60 times larger than that of the un-doped crystal. (C) 2017 Elsevier B.V. All rights reserved.