Gas-liquid flow dynamics and CO2-monoethanolamine absorption performances of an oscillating countercurrent packed bed were analyzed by means of a transient 3D nonisothermal two-fluid flow model with a goal to understand the behavior of scrubbing units on-board floating production, storage and offloading platforms. Gas-liquid flow deviation from axial symmetry was significant at larger vessel inclinations prompting noticeable liquid accumulation in the column lowermost area. Conversely, in static vertical and slightly inclined columns only a reduced fraction of the liquid was subject to transverse segregation. Externally-generated column oscillations brought about complex secondary flows in radial and tangential directions resulting in oscillatory patterns with amplitude and propagation frequency affected by the packed bed oscillations. CO2 abatement in inclined and asymmetrically oscillating columns suffered perceptible deviations with respect to vertical configuration while symmetrically oscillating columns gave rise to CO2 performances oscillating around the steady-state solutions of the vertical column. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 1064-1076, 2017