Cu-containing, apatite-type phosphate-silicate solid solutions, La (x) Ca10-x (PO4)(6-x) (SiO4) (x) Cu (y) O (z) (x = 3, 5, and 6), were synthesized by an impregnating method into the channels of apatite-type lattice by heat treatment after Cu loading. The unit cell volume of the apatite increased with increasing amount of Cu, y = 0-0.6 for x = 3 and 6, indicating successful incorporation of Cu into the channels of the apatite lattice. The result of Rietveld analysis of a La5Ca5(PO4)(SiO4)(5)Cu (y) O (z) (x = 5) sample indicated that the distribution of La3+ and Ca2+ cations in both 4f and 6 h sites were maintained during Cu incorporation. X-ray photoelectron spectroscopy and thermogravimetric analyses revealed that oxidation and reduction of Cu species occurred during heating up to 1100 A degrees C and cooling in air, respectively. In addition, high-temperature X-ray diffraction analysis of the La3Ca7(PO4)(3)(SiO4)(3)Cu0.6O (z) (x = 3) sample in the temperature range from 500 to 1100 A degrees C revealed that reversible incorporation/deposition of Cu occurred, accompanied by Cu oxidation/reduction.