J.P.C.Greenlees ``Rational O(2)-equivariant cohomology theories.'' 8 pp A complete algebraic model is given for rational O(2)-spectra. The main input is the model for SO(2)-spectra described in ``Rational S1-equivariant stable homotopy theory'', and the special case of ``Rational Mackey functors for compact Lie groups I'' applying to O(2). It turns out that any O(2)-spectrum is described by an SO(2)-spectrum with O(2)/SO(2)-action, together with an equivariant sheaf over the space of dihedral subgroups of O(2).