Different compositions of apatite-type La10Si6-xWxO27+delta ceramics are prepared successfully by the high-temperature solid state reaction route. Crystal structure and electrical properties of La10Si6-xWxO27+delta ceramics are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). La10Si6-xWxO27+delta(x = 0.1, 0.2, 0.3, 0.4, 0.5) ceramics consist of a hexagonal apatitetype structure and a small amount of La6W2O15 phase of orthorhombic structure but no La2SiO5 phase. The diffraction peaks of the hexagonal apatite-type structure shift to the low angle side with doping the W6+. When the content of hexavalent tungsten is beyond 0.1, rod-like grains of La10Si6-xWxO27+delta ceramics are replaced gradually by equiaxed apatite-type grains, and some fine particles of La6W2O15 are observed at grain boundaries. These La6W2O15 particles are non-conducting materials and lead to the increase in grain impedance and grain boundary impedance of La10Si6-xWxO27+delta ceramics gradually when the content of hexavalent tungsten is beyond 0.2. However, the solid solubility of W6+ in the lattice of apatite-type structure reaches the maximum when the W6+ content is at 0.1, and correspondingly the La10Si59W0.1O27.1 ceramic has the highest total conductivity of 4.45 x 10(-2) S cm(-1) at 1073 K. (C) 2015 Elsevier B.V. All rights reserved.