N-alkyl or arenyl-4-acetylamide-1,8-naphthalimides (NA) were synthesized by reaction of 4-acetylamide-1,8-naphthalic acid with organic amines. Optical properties were studied in the UV-visible region. By using Joule evaporation thin films of the NA, the double layer of EL devices (ITO/PVK/NA/Al) were fabricated. Yellow and green EL emission at around 569.0-504.2 nm was observed. II was found that the emission wavelength of the devices using naphthalimides with bulkier N-alkyl groups shifted to red while the emission wavelength of those devices using naphthalimides with N-arenyl substituted groups shifted to blue. This is identified with the results calculated by the MINDO/3 model. Moreover, experimental results revealed that the Joule heat by non-radiative decay has a significant affect on the device life, and the life of the device using naphthalimide compounds with high melting points is longer than that of the device fabricated using those with low melting points.