Oxides and carbon are commonly used as supports for gold nanoparticles, but metal salts are barely considered as suitable supports. Our group recently communicated that gold nanoparticles supported on nanosized LaPO4 (6-8 nm) are active for CO oxidation (Yan et al., Angew Chem Int Ed 45:3614, 2006). In the current work, we systematically developed an array of Au/M-P-O catalysts and tested them for catalytic activity and stability. It was found that 200 degrees C-pretreated Au/M-P-O (M = Ca, Fe, Co, Y, La, Pr, Nd, Sm, Eu, Ho, Er) show high CO conversions below 50 degrees C, and 500 degrees C-pretreated Au/M-P-O (M = Ca, Y, La, Pr, Nd, Sm, Eu, Ho, Er) show high CO conversions below 100 degrees C. These samples were characterized by ICP-OES, BET, XRD, TEM, SEM, and H-2-TPR. The stability of selected catalysts was studied as a function of time on stream. This work furnishes a new catalyst system for further fundamental and applied research.