2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/75212The aim of this paper is to study compact 5--manifolds which admit fixed point free circle actions. The first result implies that the torsion in the second homology and the second Stiefel--Whitney class have to satisfy strong restrictions. We then show that for simply connected 5--manifolds these restrictions are necessary and sufficient.Geometric TopologyDifferential Geometry57S15 (primary) 53C25 (secondary)text