Let A be a unital C*-algebra and let be a one-parameter automorphism group of A. We consider QSS(A), the set of all quantum symmetric states on *1 A that are also KMS states (for a fixed inverse temperature, for specificity taken to be -1) for the free product automorphism group *1 . We characterize the elements of QSS(A), we show that QSS(A) is a Choquet simplex whenever it is nonempty and we characterize its extreme points.
