The combination of heterogeneously catalysed chemical reactions and distillation in a catalytic distillation process provides several advantages. However, designing catalytic distillation columns remains a challenge. Different models of the process as well as new structured catalytic column internals have been developed. However, a lack of experimental investigation of packing properties makes it more difficult to model the process accurately. One of the important properties is the residence time distribution (RTD) affecting both reaction and separation performance. This paper presents selected results from the experimental programme of the EU project 'Intelligent column internals for reactive separations (INTINT)'. Two types of structured catalytic packings, KATAPAK((R))-S from Sulzer and MULTEPAK((R)) from Montz, each of them in two different constructions, are the subjects of the investigations presented here. RTD was studied experimentally using a tracer technique in 55 mm i.d. test column. Liquid hold-up and axial dispersion coefficients have been derived from RTD curves recorded during experiments and can be used for modelling the catalytic distillation process. The derived conclusions allow an evaluation of the column internals and facilitate an improved design with respect to the investigated properties. (c) 2004 Elsevier B.V. All rights reserved.