Monofunctionalized alkylimido derivatives of hexamolybdate, (Bu4N)2[Mo6O18(≡N–R)] (R = methyl, Me; ethyl, Et; n-propyl, n-Pr; i-propyl, i-Pr; n-butyl, n-Bu; t-butyl, t-Bu; cyclohexyl, Cy; n-hexyl, Hex; and n-octadecyl, Ode), have been prepared in high purity and good yield by the reaction of [Bu4N]4[α-Mo8O26] with appropriate aliphatic amine hydrochlorides in anhydrous acetonitrile, using N,N′-dicyclohexylcarbodiimide (DCC) as the dehydrating agent. Eight compounds have been determined by single crystal X-ray diffraction analysis and all compounds have been studied with 1H-NMR, IR, UV-vis, ESI mass spectrometry and cyclic voltammetry. A structural and 1H-NMR study show β hydrogen atoms of those alkylimido derivatives of hexamolybdate have strong Brønsted acidity compared to the hydrogen atoms in other positions.