  Weak field Hall resistance Rxy(T) of the 2D electron system in Si was
measured over the range of temperatures 1-35 K and densities, where the
diagonal resistivity exhibits a ``metallic'' behavior. The Rxy(T) dependence
was found to be non-monotonic with a maximum at temperatures Tm~0.16Tf. The
Rxy(T) variations in the low-temperature domain (T<Tm) agree qualitatively with
the semiclassical model, that takes into account a broadening of the
Fermi-distribution solely. The semiclassical result considerably exceeds an
interaction-induced quantum correction. In the ``high-temperature'' domain
(T>Tm), the Rxy(T) dependence can be qualitatively explained in terms of either
a semiclassical T-dependence of a transport time, or a thermal activation of
carries from a localized band.
