A packed bed operated with descending gas liquid cocurrent flows in slanted configuration to force trickle flow pattern to segregate due to gravity was studied, in addition to dependences to inclination angle of liquid saturation and pressure drop. Inception of pulse flow regime could take place regardless of inclination angle and the transition from segregated/trickle regime to pulse flow regime was experimentally determined. The Grosser et al. flow regime transition model was modified by considering only axial components of the gas and liquid superficial velocities to predict the slant-dependent shifts in transition from segregated/trickle to pulse flow and was found to agree with experimental data. Pulse flow regime at different inclinations was characterized with respect to frequency, velocity, and shape of pulses. Bed obliquity was unveiled as a new artifice to pulse fow modulation with possible prospects for catalytic reactions requiring antagonistically high-interaction regime mass transfer coefficients and partial wetting. (C) 2010 American Institute of Chemical Engineers AIChE J, 56: 3189-3205, 2010