In this paper, we show that the p-adic K-theory of a connected p-compa
ct is the ring of invariants of the Weyl group action on the K-theory
of a maximal torus. We apply this result to show that a connected fini
te loop space admits a maximal torus if and only if its complex K-theo
ry is lambda-isomorphic to the K-theory of some BG, where G is a compa
ct connected Lie group.