Abstract Using a variational procedure within the effective mass approximation, we have calculated the influence of an applied electric field and hydrostatic pressure on the shallow‐impurity‐related optical properties in a rectangular‐transverse section GaAs–Ga 1– x Al x As quantum well wire. The electric field is applied in the plane of the transverse section of the wire and different angular directions have been considered. The results presented are for the impurity binding energy, its corresponding density of impurity states, and impurity‐related transition energy and polarizability. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)