Optimal basis sets within the perturbed Hartree—Fock theory have been found for the first-order wavefunction for the hydrogen fluoride molecule for the operators x, z, Mx (F), and Mx (H). These sets have yielded calculated values of the polarizability components, magnetic susceptibility, magnetic shielding at H and F, rotational magnetic moment and spin rotational constants of both H and F. Excellent agreement with experimental molecular-beam values is found for the rotational magnetic moment and the spin rotation constants. Good results were obtained for the magnetic properties only if the origin is chosen at the F atom. Maps are presented for the first-order change of the electron density in the presence of an electric field, but, owing to the asymmetry of the charge distribution, reliable maps of the first-order induced current density in the presence of a magnetic field could not be obtained.