(2 + 1) Resonance enhanced multiphoton ionization (REMPI) spectra were recorded for 2-butanone to study its photoionization dynamics Two-photon excitation (53 200-55 000 cm(-1) and 57 000-59 500 cm-1) was Used to prepare (lie molecule in the 3s and 3p Rydberg states, respectively Vibrational transitions in the spectrum were assigned with the aid of A initio calculations as well as pholoelectron imaging results. Photoelectron imaging data ill the 3s Rydberg region exhibits a vibrational progression in the CCOC deformation mode. in the ionic State superimposed oil in otherwise diagonal (delta v = 0) ionization. Photoelectron imaging data in the 3p Rydberg region shows 3p-3s Rydberg-Rydberg mixing. The ionization energy obtained directly from the 3p photoelectron Imaging is 9 541 eV