  We construct an anomaly free supersymmetric U(1)' model with a secluded
U(1)'-breaking sector. We study the one-loop effective potential at finite
temperature, and show that there exists a strong enough first order electroweak
phase transition for electroweak baryogenesis (EWBG) because of the large
trilinear term $A_h h S H_d H_u$ in the tree-level Higgs potential. Unlike in
the MSSM, the lightest stop can be very heavy. We consider the non-local EWBG
mechanism in the thin wall regime, and find that within uncertainties the
observed baryon number can be generated from the $\tau$ lepton contribution,
with the secluded sector playing an essential role. The chargino and neutralino
contributions and the implications for the Z' mass and electric dipole moments
are briefly discussed.
