  The dynamics of five dimensional Wilson line phases at finite temperature is
studied in the one-loop approximation. We show that at temperatures of order T
\sim 1/L, where L is the length of the compact space, the gauge symmetry is
always restored and the electroweak phase transition appears to be of first
order.
  Particular attention is devoted to the study of a recently proposed five
dimensional orbifold model (on S1/Z2) where the Wilson line phase is identified
with the Higgs field (gauge-Higgs unification). Interestingly enough, an
estimate of the leading higher-loop ``daisy'' (or ``ring'') diagram
contributions to the effective potential in a simple five dimensional model,
seems to suggest that the electroweak phase transition can be studied in
perturbation theory even for Higgs masses above the current experimental limit
of 114 GeV. The transition is still of first order for such values of the Higgs
mass. If large localized gauge kinetic terms are present, the transition might
be strong enough to give baryogenesis at the electroweak transition.
