  We search for time-dependent solutions for the 5-dimensional system of a
scalar field canonically coupled to gravity. Time-independent and
time-dependent scalar field configurations with the most general homogeneous
and isotropic 4D metric are considered. For the case of time-independent scalar
field, the time evolution of the scale factor is obtained for different values
of the spatial curvature $k=0,\pm 1$. In the case of time-dependent scalar
field, two classes of solutions are discussed and an extension of the
superpotential formalism is proposed.
