A continuous micro-pilot unit has been designed to convert petroleum residues with dispersed catalysts. Once-through and recycling modes can be operated. Several operating conditions (residence times and temperatures) have been investigated using the molybdenum naphthenate as catalyst precursor (600 ppm). The micro-pilot hydrodynamics has been characterized via a cold mockup by Residence Time Distribution. Whatever the mode used, the conversion, product yields and average molecular weights depends only on residence time and temperature. (C) 2014 Elsevier B.V. All rights reserved.