  We develop a theory of current-voltage (I-U) characteristics for
superconductor-normal metal-superconductor (SNS) junctions. At small voltages
and sufficiently low temperatures the I-U characteristics of the junction is
controlled by the inelastic relaxation time, \tau_{in}. In particular, the
linear conductance is proportional to, \tau_{in}. In this regime the I-U
characteristics can be expressed solely in terms of dependence of the density
of states in the normal region, \nu(\chi), on the phase difference of the order
parameter across the the junction. In contrast, at large voltages the I-U
characteristics of the device is controlled by the elastic relaxation time,
\tau_{el}, which is much smaller than the inelastic one.
