SUMMARYWe present an ab initio SCF-MO study of the static dipole polarizability of some neutral and charged species of naphthalene (C10H8) q , (q = −2, −1, 0, +1, +2). The charged species involve additions and removals of electrons to and from the HOMO and LUMO π-electron orbitals. The polarizability calculations were performed using the Coupled Perturbed Hartree-Fock method, and in addition, we used direct analytical differentiation of the energy expression. We used a series of split valence basis sets augmented with sp diffuse and polarized functions STO/6-31+G(md,np, (m = n = 1, 2, 3), and all geometries were fully optimized. Molecular structure optimizations were generally started from the geometry predicted for neutral naphthalene with D2h symmetry at the HF/6-31G** level of theory.The Hartree-Fock results indicate that the anisotropies of the components of the dipole polarizability tensor of neutral naphthalene (q = 0) are in agreement with our own previous theoretical calculations and with the experimental values corresponding to laser Stark spectroscopy in a naphthalene molecular beam. This agreement with experimental results can be further improved with extension of the number of polarized functions in the basis set.We also analyse the effect of the negative and positive charges on the naphthalene molecule on the polarizability tensor components. The variation of molecular geometry also plays a part in these changes.