  We report the discovery of the coolest subdwarf reported to date. The star
LSR1425+7102 was discovered in our survey for faint high proper motion stars in
the northern sky. Follow-up spectroscopy revealed the star to be a very red
object with the characteristic signature of M subdwarfs: strong CaH bands but
relatively weaker TiO bands. The CaH molecular band at $\approx\lambda$6900\AA\
is particularly strong. By extrapolating the empirical relationship between the
strength of the CaH molecular band and the subdwarf subtype, we conclude that
LSR1425+7102 is the first star to be discovered with spectral type sdM8.0.
