Ninhydrin (1) reacted with weak nitrogen nucleophiles (2a-2f) in the presence of H2O/EtOH medium to give the corresponding indeno-imidazole derivatives (3a-3d) and ninhydrin-nucleophile adducts (3e-3f). The structures of the compounds (3a-3f) were confirmed by their UV, IR, 1H NMR, 13C NMR spectra and elemental analyses. The synthesized compounds were evaluated for their antimicrobial activity by Kirby-Bauer disk diffusion method. Most of the compounds showed good to moderate antimicrobial activity.