The electronic absorption spectra of thiophen and of some deuterated thiophens have been studied in the range 2500–1400 A. Three electronic transitions, with origins at 41 595, 48 330 and 53 270 cm–1 in C4H4S and two Rydberg series leading to the limit 71 570 cm–1 were analyzed. The broadness of the bands prevents the identification of the symmetry of the upper states by analysis of band contours. Only progressions of totally-symmetric vibrations appear in the vibrational structure of the first three transitions, indicating that they are allowed. From the small changes of the vibrations in respect to the ground state, and from the intensity distribution in the vibrational structure, it can be concluded that the geometry of the Rydberg states is close to that of the ground state.