Synthesis, X-ray diffraction, IR and luminescence spectroscopic studies of the monohydrate of pentachloroantimonate(III) of doubly protonated ciprofloxacin (C₁₇H₁₉N₃O₃F)SbCl₅ · H₂O (I) were performed. The structure of I is formed by SbCl₆ octahedra combined into polymeric chains [SbCl₅] _n ²ⁿ⁻ through common vertices, ciprofloxacinium cations (CfH₃)²⁺, and water molecules linked by hydrogen bonds. CfH is protonated at the carbonyl oxygen atom and the terminal nitrogen atom of the piperazinyl group. The electronic and geometric aspects determining the luminescence properties of I and of related compounds are discussed.