Picosecond time-resolved IR spectra of phenol-(NH3)(3) have been measured by UV-IR-UV ion dip spectroscopy for the first time. It was found that the time-evolution of two vibrational bands at 3180 and 3250 cm(-1) is different from each other. The results show that two transient species are generated from the photo-excited phenol-(NH3)3 cluster. From ab initio calculation, the transient species are assigned to two isomers of (NH3)(2)NH4.