Two sets of wire mesh tomography sensors have been developed for the study of liquid maldistribution in trickle bed reactors. The technique, based on the one used by Prasser et al. [H.M. Prasser, A. Bottger, J. Zschau, A new electrode-mesh tomograph for gas-liquid flows, Flow Meas. Instrum. 9 (1998) 111-119] in bubble columns, uses two horizontal planes of wires placed at fixed bed depths to measure the presence of a conductive liquid between them. Being only slightly invasive, the conceived wire mesh tomography device allows estimation of liquid concentration over a cross-sectional area of the column with a spatial resolution of 313 pixels. Examples of wire mesh tomography measurements inside a trickle bed reactor using different liquid distributors are presented here. Results are satisfying and wire mesh tomography appears to be a promising technique for the study of liquid maldistribution in trickle beds of non-porous particles. (c) 2007 Elsevier B.V. All rights reserved.