A series of benzoyl para- and meta-substituted benzanilides (BAs) and N-methylbenzanilides (MBAs) were synthesized and their absorption and fluorescence spectra in nonpolar solvent cyclohexane were investigated. Quantum mechanical calculations indicated that the ground state BAs existed preferentially in the trans configuration, whereas MBAs existed in the cis configuration, and benzoyl substitution hardly changed the ground-state structure in the same series. It was observed that all of the synthesized compounds displayed dual fluorescence in cyclohexane, i.e., a normal emission at ca. 330 nm and an abnormal long-wavelength fluorescence at around 500nm. Although the normal emission of both BAs and MBAs did not show obvious variation, the long-wavelength emission shifted strongly to the red with increasing electron-withdrawing ability of the substituent at the benzoyl moiety. The emission energies of the long-wavelength fluorescence of BAs and MBAs in cyclohexane were found to vary linearly with the Hammett substituent coefficient