Eleven new oxides, derived from yttrium barium copper oxide by replacing the square-planar copper [Cu-O-4] Of the basal plane o: the triple perovskite-based structure with octahedral Cr-IV, have been prepared at high pressure and temperature. Their crystal structures have been determined, and their complex microstructure has been established by means of high-resolution electron microscopy and electron diffraction. The materials have a general formula of CrSr2RECU2O8 (RE = La, Pr, Nd, Eu, Gd, Tb, Dy, Y, Ho, Er, and Lu); they are tetragonal, show the symmetry of space group P4/mmm, and do not appear to be superconducting.