Looking for compounds Cs2MF4 the cesium richest composition we found at M(II) = Co, Ni was Cs7M4F15. X-ray single crystal work revealed a layer structure (P21/c, Z=2), built up from face-sharing double octahedra M2F9 which are mutually connected via three of their vertices. Some interatomic distances are given in Table I, along with data of six novel compounds Ba2AM2F9 (R3m, Z=3). The puckered layer structure of the latter consists of single octahedra, sharing three corners in a fac-position. It derives from the hexagonal perovskite structure of CsCoF3 by omitting the central cations within the groups of three face-sharing octahedra.