  We present a microscopic approach to dynamical pionisation of the hot
quark-gluon matter formed in ultrarelativistic heavy ion collisions. The time
evolution of the system is described assuming that quarks undergo Brownian
motion in a thermal bath provided by the gluons. The rate of hadronization as
well as the time dependence of the temperature of the system are seen to be
quite sensitive to the QCD $\Lambda$ parameter. Even in a non-equilibrium
scenario, we find that there appears a clear hint of a first order phase
transition.
