The effect of the CH3 group on the lifetime of the S-1 state of the p-cresol(NH3) complex was investigated by means of REMPI, LIF, DF spectroscopy and ab initio calculations. At variance with PhOH(NH3) for which vibrational-mode specificity was reported, the lifetime of the S-1 state of the p-cresol(NH3) complex decreases monotonically upon vibrational excitation indicating that randomization of energy takes place at low excitation energy. This result is analyzed as the consequence of a stronger coupling of the complex intermolecular modes with those of the CH3 group. (C) 2009 Elsevier B.V. All rights reserved.