A single-crystal X-ray diffraction analysis of the mixed salt of hydroxypyridonate Pu(IV) complexes is presented; [Pu(1,2-HOPO)(3)(H2O)(2)center dot ClO4] [Pu(1,2-HOPO)(4)] crystallizes in P2(1) with the asymmetric unit containing two distinct eight-coordinate Pu(IV) complexes, one tris(bidentate) and the other tetrakis(bidentate). The structure of this complex is compared to the analogous Ce(IV)- and Th(IV)-1,2-HOPO structures.