Two conformational isomers of the aromatic hydrocarbon n-butylbenzene have been studied using two-color MATI (mass analyzed threshold ionization) spectroscopy to explore the effect of conformation on ionization dynamics. Cationic states of gauche-conformer III and anti-conformers IV were selectively produced by two-color excitation via the respective S, origins. Adiabatic ionization potentials of the gauche-and anti-conformations were determined to be 70146 and 69872 +/- 5 cm(-1) respectively. Spectral features and vibrational modes are interpreted with the aid of MP2/cc-pVDZ ab initio calculations, and ionization-induced changes in the molecular conformations are discussed. Complete basis set (CBS) ab initio studies at MP2 level reveal reliable energetics for all four n-butylbenzene conformers observed in earlier two-color REMPI (resonance enhanced multiphoton ionization) spectra. For the So state, the energies of conformer III, IV and V are above conformer I by 130, 289, 73 cm(-1), respectively. Furthermore, the combination of the CBS calculations with the measured REMPI, MATI spectra allowed the determination of the energetics of all four conformers in the S-1 and D-0 states.