The reaction of hydrazine and benzophenone hydrazone with 2-acetonitrilium closo-decaborate (X)[B₁₀H₉NCMe] (X = PhCH₂PPh₃, Ph₄P, ⁿBu₄N) proceeds in MeCN or THF at RT for 30 min giving 2-iminium closo-decaborates (X)[B₁₀H₉N(H)[dbnd]C(Me)NNR₂] (R₂ = (H)₂, CPh₂; X = PhCH₂PPh₃, Ph₄P, ⁿBu₄N) that were isolated in 77–88% yields. These species were characterized by IR, ¹H{¹¹B}, ¹¹B{¹H}, and ¹³C{¹H} NMR spectroscopies, HRESI-MS, and molar conductivity. Two compounds were also characterized by single-crystal X-ray diffraction. Emission spectra of the obtained compounds consist of one broad band with the maximum in the 506–516 nm range. Nanosecond lifetimes of the closo-decaborate clusters confirm fluorescent character of the emission. Derivatization of the nitrilium ligand results in increase of luminescence up to 42% as compared to the starting nitrilium closo-decaborate.