  The B -> D^{(*)} K^- K^{(*)0} decays have been observed for the first time.
The branching fractions of the B -> D^{(*)} K^- K^{(*)0} decay modes are
measured. Significant signals are found for the B -> D^{(*)} K^- K^{*0} and B^-
-> D^0 K^- K^0_S decay modes. The invariant mass and polarization distributions
for the K^-K^{*0} and K^-K^0_S subsystems have been studied. For the K^-K^{*0}
sybsystem these distributions agree well with those expected for two-body B ->
D^{(*)} a_1^-(1260) decays, with a_1^-(1260) -> K^- K^{*0}. The analysis was
done using 29.4 fb^{-1} of data collected with the Belle detector at the e^+
e^- asymmetric collider KEKB.
