The aim of this article is to investigate the influence of feed stress on the velocity profile of a powder material along the vertical axis in the space between the rollers of a roll compactor. At a certain combination of frequency of rotation of the rollers and the piston feed, the friction between the particles of the mass as it is dragged between the rollers increases, which means that the mobility of the material in the space between the rollers is restricted. In a detailed investigation of this undesired effect, a high-speed CCD (charge-coupled device) camera was used. An experiment was designed and conducted to record, using digital particle image velocimetry (DPIV) methods, the velocity of the mobile particulate material in its passage through the individual zones between the rollers. Using this methodology, it was possible to identify the velocity profile of the powder material along the vertical axis of the roll compactor. (C) 2014 Elsevier B.V. All rights reserved.