This paper presents results of a large-scale experimental study devoted to establishing the relation between the quality of initial gas (mal)distribution, as created by common liquid collecting devices used in redistribution sections of packed columns, and the hydraulics of a structured packing bed. Both dry and wet bed experiments were conducted with air-water system under ambient conditions, using a 1.4 m i.d. Plexiglas column, including also high liquid loads. Additional, controlled gas maldistribution studies were conducted to observe the bed height needed to smooth out various types of initial maldistribution. From dry and wet experiments, it appeared that the type (severity) of initial gas maldistribution influences the pressure drop of the bed. (C) 2003 Elsevier B.V. All rights reserved.