Functional inorganic materials, mostly oxides but also fluorides, sulfides, or nitrides has led to the development of many modern technologies. The usual way to improve the chemical and physical properties of these materials was the cationic substitution in order to tune the chemical bonding. These “single anions” materials have been intensively studied during the past decades. It is also possible to tune the properties of the materials by substituting anions instead of cations, giving rise to the “mixed-anions” research field. As the anions can exhibit very different chemical characteristics (electronegativity, valence, polarizability…), mixing anions can allow the stabilization of new compounds with exotic coordination geometries and various physical properties. In transition metal based hydroxyfluorides, fluoride (F-) and hydroxide (OH-) ligands coordinating metals are coexisting in the structure. The similarities between these anions (charge, valence, size…) are facilitating the anionic substitution. The large difference of electronegativity/polarizability of these anions permit a tunability of chemical bonds, giving rise to a fine control on the structural features (coordination polyhedra, hydrogen bondings…) and consequently on the chemical and physical properties such as acido-basicity, thermal stability, or transport properties. The presentation concerned the preparation and the characterization of copper-based hydroxyfluorides. Long-range and short-range order characterizations were performed in order to understand better the impact of the F/OH ratio on the structural features and the physico-chemical properties.