Reaction of [SbW9O33]9- with [Pt(H2O)2(OH)4] results in the first example of the mixed addenda Anderson-Evans type PtIV{SbV(OH)2}WVI5O22]7- anion, isolated and characterized as K6Na2[Pt{Sb(OH)2}W5O22](NO3)0.1(OH)0.9̇11H2O (1).