We have synthesized by solid state chemistry and structurally characterized by single crystal X-ray diffraction two new cluster compounds, KNb 6 Cl 1 0 F 5 and CsNb 6 Cl 8 F 7 . KNb 6 Cl 1 0 F 5 is a Ta 6 Cl 1 5 derived structure, whereas CsNb 6 Cl 8 F 7 exhibits a primitive framework derived from Nb 6 F 1 5 . In both structures, fluorine and chlorine are randomly distributed on the ligand positions, but in CsNb 6 Cl 8 F 7 fluorine fully occupies the apical positions. The comparison between the geometrical parameters of the title compounds and those observed in previously isolated Nb 6 chlorofluorides, halides and fluorides, allows specification of the influence of fluorine in niobium cluster chemistry.