This work reports the synthesis, characterization and catalytic activity for CO oxidation of gold catalysts supported on calcium hydroxyapatite. On both, the hydroxyapatite support and the gold-supported hydroxyapatite catalyst, the CO conversion shows a peak near 100% of conversion at room temperature. The generation of structural vacancies by interaction of CO with the solid provokes the formation of peroxide species in the presence of gaseous oxygen, which seems to be responsible of this high conversion of CO at room temperature. Moreover, the influence of the pre-treatment temperature on the activity has been observed and related with the elimination of carbonate species and the generation of structural defects in the apatite structure, which are able to modify the gold oxidation state. (C) 2008 Elsevier B.V. All rights reserved.