A new Schiff base compound(Z)-1-[(4-amino-2,3,5,6-tetramethylphenylamino)methylene]-1,8a-dihydronaphthalen-2(3H)-onewas synthesized by the reaction of 2-hydroxy-1-naphthaldehyde with 2,3,5,6-tetramethyl-p-phenylenediamine. It was investigated by using elemental analysis, IR, 1H-NMR, 13C-NMR, UV-Visible-spectroscopy, and X-ray-crystallography techniques. Its UV-Visible spectra were examined in polar and nonpolar solvents. The Schiff base studied exists in enol-imine keto-amine form in DMSO ethanol, chloroform, and benzene solution. The keto-amine tautomer was found to be dominant in both the phases. The (Z)-1-[(4-amino-2,3,5,6-tetramethylphenylamino)methylene]-1,8a-dihydronaphthalen-2(3H)-one molecule is not planar. It contains a strong intramolecular N-H...O hydrogen bond between the amine and oxo group [N1 and O1=2.591(2) angstrom], the H atom being essentially bonded to the N1 and O1 atoms.