  We study the occurrence of a strong first-order electroweak phase transition
in composite Higgs models. Minimal constructions realising this scenario are
based on the coset SO(6)/SO(5) which delivers an extended Higgs sector with an
additional scalar. In such models, a two-step phase transition can be obtained
with the scalar singlet acquiring a vacuum expectation value at intermediate
temperatures. A bonus of the Nambu-Goldstone boson nature of the scalar-sector
dynamics is the presence of non-renormalisable Higgs interactions that can
trigger additional sources of CP violation needed to realise baryogenesis at
the electroweak scale. Another interesting aspect of this scenario is the
generation of gravitational wave signatures that can be observed at future
space-based interferometers.
