The band origins of the S,, So electronic transition and the ionization energies of Cl-35 and Cl-37 isotopomers of p-chlorophenol are found to be the same, with the values of 34813 +/- 2 and 68104 +/- 5 cm(-1), respectively. Although the general spectral features of these two isotopomers are similar, frequencies of some vibrational modes are slightly different by a few wavenumbers. This frequency shift somewhat depends on the degree of the Cl atom involved in the molecular motion. (c) 2006 Elsevier B.V. All rights reserved.