The paper presents experimental results concerning hydrodynamic aspects in a trickle-bed reactor, in which both fluid phases (gas and liquid) are fed concurrently downward. The static and dynamic liquid holdup fractions were measured in a trickle-bed reactor (inner reactor diameter 0.034 m) packed with different porous and nonporous particles at very low liquid mass flow rates using the drainage technique. The liquid Reynolds number Re_L was in the range of 0.08-1.2 and the gas Reynolds number Re_G in the range of 0.13-2.9. The measurements were performed with organic liquids and hydrogen and nitrogen as gas phases. The results are presented graphically. It was shown that the ratio of the reactor diameter to the particle diameter and liquid Reynolds number affect on the liquid holdup. The dynamic liquid holdup increases with an increase in the liquid Reynolds numbers and with a decrease in the particle diameter. The effect of the gas flow rate on the liquid holdup can be neglected. Correlations are derived that are valid for very low liquid Reynolds numbers and are compared to the literature.