The 1-[N-(methyl)-(3,5-dimethylphenylamino)]methylnaphthalene (chemical formula C20H21N) was prepared by means of a condensation between alpha-naphthylaldehyde and 3,5-dimethylaniline in anhydrous ethanol to obtain the aldimine (1) which was reduced with NaBH4 to afford the 1-[N-(3,5-dimethylphenylamino)]methylnaphtalene (2), and finally, the compound (3) was obtained by N-alkylation reaction of (2) with methyl iodine (CH3I) and potassium carbonate (K2CO3) in acetone. Final compound (3) was purified by chromatographic column. The XRPD pattern for the new compound, 1-[N-(methyl)-(3,5-dimethylphenylamino)]methylnaphthalene, was obtained. This compound crystallizes in monoclinic system with space group P21/a (No. 14) and refined unit-cell parameters a=13.260(4) Å, b=15.495(5) Å, c=7.719(5) Å, β=90.19(6), and V=1586(1) Å3.