When fluid flows throught porous layer there are energy losess due to suface friction and resistance due to the shape of the particles which form that layer. The total loss of fluid energy is manifested by a pressure drop in the system, which can be determined experimentally and theoretically. In this work characterization of three porous layers whose particle sizes differ significantly was performed. The influence of the height of the porous layer and fluid superficial velocity on pressure drop in the system has been investigated as well. The experimental determined pressure drop were then compared with those obtained using theoretical expressions. The orientational characterization of the porous layer can be performed using the relatively easily measurable characteristics of the questioned porous layer. Experimental examinations have confirmed that increasing the height of the porous layer as well as increasing the fluid superficial velocity, the pressure drop in the system increases significantly. Comparing theoretically and experimentally determined values of pressure drop, the smallest deviations are observed when Ergun's equation has been applied. This is especially emphasized in the case of the porous layer composed of the smallest examined particles (dĉ,ekv = 0.0025 m). However, for more concrete conclusion, additional examinations of porous layers in a larger range of particle sizes are suggested.