The decay of the omega meson in a heat bath of thermally excited pions is s
tudied within the framework of real-time thermal field theory using an appr
opriate effective Lagrangian. We show that the omega meson spectrum broaden
s considerably at temperatures T > 100 MeV, primarily because of omega pi -
-> pi pi reactions in the thermal environment. @ 2001 Published by Elsevier
Science B.V.