The adiabatic ionization potentials Of Cs2 and Cs3 are measured in a pulsed supersonic jet using one-photon ionization and time-of-flight mass spectrometry. The ionization energies are determined to be IP(CS2) = 29205.5 +/- 1.0 cm-1 and IP(Cs3) = 24690 +/- 30 cm-1. The dissociation energy of the Cs2+ ion is determined as D(e)(Cs2+) = 5845.7 +/- 2.0 cm-1.The determined ionization energy Of CS2 and the dissociation energy of Cs2+ ion show good agreement with theoretical predictions.