  We report on field-induced variations of the microwave surface resistance at
9.6 GHz of Ba(0.6)K(0.4)BiO(3) crystals. Energy losses have been investigated
as a function of the static magnetic field in the range of temperatures 4.2 K -
Tc. By analyzing the experimental results in the framework of the Coffey and
Clem model we determine the temperature dependence of the first-penetration
field, upper critical field and depinning frequency. The results show that the
pinning energy of this bismuthate superconductor is weaker than those of
cuprates.
