We investigate, both analytically and by computer simulation, the kinetics
of a microscopic model of hard rods adsorbing on a linear substrate. For a
small, but finite desorption rate, the system reaches the equilibrium state
very slowly, and the long-time kinetics display three successive regimes:
an algebraic one where the density varies as 1/t, a logarithmic one where t
he density varies as 1/ln(t), followed by a terminal exponential approach.
A mean-field approach fails to predict the relaxation rate associated with
the latter. We show that the correct answer can only be provided by using a
systematic description based on a gap-distribution approach.