  The Higgs potential of the minimal nonminimal supersymmetric standard model
(MNMSSM) is investigated within the context of electroweak phase transition. We
investigate the allowed parameter space yielding correct electroweak phase
transitoin employing a high temperature approximation. We devote to
phenomenological consequences for the Higgs sector of the MNMSSM for
electron-positron colliders. It is observed that a future $e^+ e^-$ linear
collider with $\sqrt{s} = 1000$ GeV will be able to test the model with regard
to electroweak baryogenesis.
