The energetic properties of N-phenyl-1,2-naphthylamine have been determined using a series of theoretical calculations and their geometries have been optimized using Hartree-Fock (HF) and Density Functional Theory (DFT). The structures have been examined to predict lower-lying energy structure of the title molecule within the considered potential conformations. Structural parameters and energetics, such as total energies with Zero-Point energy corrections, highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies, have been analyzed and compared between the structural isomers. 1-NPN is the most commonly used molecule for many purposes, mainly as the fluorescent probe in binding assays. When compared the two structures, we showed that 2-NPN isomers are energetically more stable than 1-NPN isomers. It is possible that 2-NPN may be favored in many applications with respect to 1-NPN, and thus its function may be understood in the light of its molecular and structural properties. (C) 2013 Elsevier B.V. All rights reserved.