The connection is discussed between the phase transitions in the hot hadronic matter and characteristic mass parameters of the non-perturbative QCD. The spectrum of the hot hadronic matter containing light coloured scalar fields in addition to ordinary quarks and gluons is investigated by means of the finite-temperature QCD sum rules. A qualitative rearrangement of the spectrum is shown to occur at some temperature T cr, which is entirely fixed by the value of the scalar field condensate 〈φ † φ〉. A variety of possible phase transitions in such a matter is considered. © 1986 Società Italiana di Fisica.