  The evolution of multiplicity distribution of a species which undergoes
chemical reactions can be described with the help of a master equation. We
study the master equation for a fixed temperature, because we want to know how
fast different moments of the multiplicity distribution approach their
equilibrium value. We particularly look at the 3rd and 4th factorial moments
and their equilibrium values from which central moments, cumulants and their
ratios can be calculated. Then we study the situation in which the temperature
of the system decreases. We find out that in the non-equilibrium state, higher
factorial moments differ more from their equilibrium values than the lower
moments and that the behaviour of the combination of the central moments
depends on the combination we choose. If one chooses to determine the chemical
freeze-out temperature from the measured values of higher moments, these
effects might jeopardise the correctness of the extracted value.
