Liquid holdup was measured as function of gas and liquid mass flow in the three-levels-of-porosity (TLP) reactor. Packing material and bed height were varied. Because a TLP reactor contains layers of catalyst there is an additional bed holdup compared to conventional trickle-bed reactors. Liquid bed holdup is composed of two parts: below the capillary fill height the interparticle pores are completely filled with liquid, above this height the liquid holdup is well described by literature relations for single-phase trickle-now. Using residence time measurements it was shown that no stagnant zones for liquid flow existed in the tested TLP packings.