  During a strongly first-order phase transition gravitational waves are
produced by bubble collisions and turbulent plasma motion. We analyze the
relevant characteristics of the electroweak phase transition in the nMSSM to
determine the generated gravitational wave signal. Additionally, we comment on
correlations between the production of gravitational waves and baryogenesis. We
conclude that the gravitational wave relic density in this model is generically
too small to be detected in the near future by the LISA experiment. We also
consider the case of a "Standard Model" with dimension-six Higgs potential,
which leads to a slightly stronger signal of gravitational waves.
