  The maximum sustainable amplitude, so-called wave breaking limit, of a
nonlinear plasma wave in arbitrary mass ratio warm plasmas is obtained in the
non-relativistic regime. Using the method of Sagdeev potential a general wave
breaking formula is derived by taking into account the dynamics of both the
species having finite temperature. It is found, that the maximum amplitude of
the plasma wave decreases monotonically with the increase in temperature and
mildly increases with increase in mass ratio.
