Diffraction coefficients are derived from an approximate solution of the governing functional difference equations to characterize the scattering by an impedance wedge illuminated at skew incidence. This solution recovers the exact known diffraction coefficients for an impedance half plane and a wedge at normal incidence. To validate the approximate solution for other wedge angles, a comparison is made with numerical data obtained from a moment method code applicable to skew incidence on a polygonal impedance cylinder. ¿ American Geophysical Union 1995