A series of gold supported on hydroxylapatite (HAP) catalysts were prepared by deposition-precipitation with urea to study the influence of calcination atmosphere, i.e., H-2, He and O-2, on the performance of the catalyst in low-temperature CO oxidation. Calcination atmosphere was found to have an important influence on the catalytic activity and stability of Au/HAP. The highest initial activity was obtained for Au/HAP-He obtained by inert He-calcination, which, however, suffered the most severe deactivation with time on stream. Calcination in oxidative O-2 environment resulted in the best stability and highest steady-state activity among the three catalysts. TEM results revealed that inert He-calcination can produce the smallest Au nanoparticles over the HAP support, which was suggested to be responsible for the highest initial activity of Au/HAP-He. Based on the CO2-TPD and in situ DRIFTS studies, the superior stability of Au/HAP-O-2 can be attributed to a limited surface basicity in this material. (C) 2010 Elsevier B.V. All rights reserved.