This work investigates the pros and cons related to the use of the electrical capacitance tomography (ECT) technique for the imaging and the quantitative characterization of flow dynamics that develop in a four-phase trickle-bed reactor. The use of ECT in non-invasive imaging is increasing continuously owing to its low cost and technical convenience when compared to other tomography methods, such as nuclear ionizing and non-ionizing tomographies. Yet, ECT is plagued by low spatial resolution, lack of multi-modality and the need for solving a very difficult inverse problem for image reconstruction. The flow dynamics that establish in a four-phase trickle-bed system (consisting of flowing gas, flowing dilute suspension consisting of a liquid and micron-range fines, as well as a static solid macroporous bed) are very complex and prone to instability. This work sets to determine in which measure ECT can be used for capturing representations of steady-state flow features as well as unsteady situations (like plug formation and preferential flowing) either simulated or measured on a lab-scale column. Many numerical algorithms for image reconstruction are investigated in the light of the needs imposed by the characteristics of the trickle-bed reactor. (c) 2005 Elsevier B.V. All rights reserved.