  We study some bulk thermodynamical characteristics, meson properties and the
nucleon as a baryon number one soliton in a hot quark matter in the NJL model
as well as in a hot nucleon matter in a hybrid NJL model in which the Dirac sea
of quarks is combined with a Fermi sea of nucleons. In both cases, working in
mean-field approximation, we find a chiral phase transition from Goldstone to
Wigner phase. At finite density the chiral order parameter and the constituent
quark mass have a non-monotonic temperature dependence - at finite temperatures
not close to the critical one they are less affected than in the cold matter.
Whereas the quark matter is rather soft against thermal fluctuations and the
corresponding chiral phase transition is smooth, the nucleon matter is much
stiffer and the chiral phase transition is very sharp. The thermodynamical
variables show large discontinuities which is an indication for a first order
phase transition. We solve the B=1 solitonic sector of the NJL model in the
presence of an external hot quark and nucleon medium. In the hot medium at
intermediate temperature the soliton is more bound and less swelled than in the
case of a cold matter. At some critical temperature, which for the nucleon
matter coincides with the critical temperature for the chiral phase transition,
we find no more a localized solution. According to this model scenario one
should expect a sharp phase transition from the nucleon to the quark matter.
