  The present contribution deals with thermodynamic aspects of the model of
Expansive Nondecelerative Universe. In this model, in the matter era a
dependence T^CBR ~ E^CBR ~ a(exp -3/4) holds for the energy of cosmic
background radiation, E^CBR and its temperature T^CBR, while the
proportionality of the energy density epsilon^CBR to the gauge factor a can be
expressed as epsilon^CBR ~ a(exp -3). The given relationships comply with
experimental observations of the cosmic background radiation as well as with a
surprising finding that the Universe expansion is not decelerated by
gravitational forces. It is rationalized that the specific entropy is
proportional to a(exp -1/4), i.e. it is gradually decreasing in time.
