<p>This study focuses on the synthesis and biological evaluation of hydrazide- and imino-functionalised imidazolium salts. All compounds were characterized using spectroscopic techniques, including NMR, FT-IR, and mass spectrometry. The synthetic route involved a four-step process: First, <i>N</i>-alkylimidazole was synthesized by reacting imidazole with alkyl halide in the presence of NaOH using DMSO as the solvent; second, imidazolium salts-functionalized ester were prepared by reacting <i>N</i>-alkylimidazole with ethyl chloroacetate in toluene; third, the corresponding hydrazide was obtained by treating the ester with hydrazine in ethanol; and the final imino-functionalised imidazolium salts were synthesized via condensation of the imidazolium salts-functionalized hydrazide with terephthalaldehyde in ethanol under mild acidic conditions. The antibacterial activity of selected derivatives was assessed against <i>Staphylococcus aureus</i> and <i>Klebsiella pneumoniae</i> using the microdilution method in 96-well microplates, with MIC values determined by ELISA microplate reader at 630 nm. Notably, 1-butyl-3-(2-hydrazinyl-2-oxoethyl)imidazolium chloride exhibited the most potent activity, with MIC values of 0.3125 mg/cm³ and 0.625 mg/cm³ against <i>S. aureus</i> and <i>K. pneumoniae</i>, respectively. Compounds 1-benzyl-3-(2-hydrazinyl-2-oxoethyl)imidazolium chloride and 1-butyl-3-(2-hydrazinyl-2-oxoethyl)benzimidazolium chloride also demonstrated strong antibacterial effects, with MICs ranging from 0.625 to 1.25 mg/cm³. Percent inhibition data further supported these findings, as most compounds achieved &gt; 90% bacterial growth inhibition at concentrations ≥ 1.25 mg/cm³. These results highlight the potential of hydrazide- and imino-functionalised imidazolium salts as promising scaffolds for the development of novel antibacterial agents.</p> Graphical abstract <p></p>