New pyrochlore-type oxides, ASrNb(2)O(6.5) (A = Li and Na), were prepared from Dion-Jacobson-type layered perovskite oxyfluorides, ASrNb(2)O(6)F. The prototype layered perovskite phases are transformed into anion-deficient pyrochlore-type oxides by heating above 600 degreesC in air. The ASrNb(2)O(6)F (A = Rb and K) and RbCaNb2O6F compounds have the layered perovskite structure, whereas the pyrochlore structure is found to be more stable than the layered perovskite in the AF-SrNb2O6 (A = Li and Na) and KF-CaNb2O6 systems.