A novel heteropolyoxopalladate structural type has been discovered: the polyoxo-15-palladate(II) [Pd(0.4)Na(0.6) subsetPd(15)P(10)O(50)H(6.6)](12-) (Pd(15)) has been prepared in a one-pot self-assembly reaction and characterized by single-crystal XRD, elemental analysis, IR, TGA, (31)P NMR and electrochemistry; preliminary catalytic studies showed that Pd(15) is active as a catalyst in alcohol oxidation by dioxygen.