A series of alkyl-functional naphthoxazine resins having various alkyl chain lengths from C1 to C18 are synthesized with a high yield and high purity by the reactions of 1,5-dihydroxynaphthalene, formaldehyde, and aliphatic amines. The proposed chemical structures of the naphthoxazines are confirmed by high-resolution mass spectrometry, H-1 nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and pyrolysis mass spectrometry studies. The alkyl-functional naphthoxazines have shown low polymerization temperature characteristics where polymerization of these monomers is achieved in the range of 150-170 degrees C yielding cross-linked polynaphthoxazines. The low-temperature polymerization characteristics and the associated thermal degradation behaviors are studied. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 3114-3123, 2013