Mass-analyzed threshold ionization (MATI) spectroscopy and two-color resonant two-photon ionization method were used for the determination of the vibrational levels of the p-xylene cation. The MATI spectrum was recorded via the 0(0) vibrationless level of the S-1 state of p-xylene. The spectrum shows a rich structure and some vibrational frequencies of the cation are determined. The experimental findings are well supported by ab initio calculation. (C) 2003 Elsevier B.V. All rights reserved.