This paper describes an implicit 1-D two-fluid hydrodynamic trickle-bed model designed to approximate the actual two-phase flow and bed void using four inclined slits consisting of a dr, a gas-(static)liquid, a (dynamic)liquid-(static)liquid and a gas-(dynamic)liquid slits. Based on the Holub et al.(1) mono-slit phenomenological approach, the model can be used to predict the frictional two-phase pressure drop, the external, dynamic and static liquid hold-ups, the pellet-scale external, dynamic and static wetting efficiency in trickle-bed reactors operated under trickle flow regime and partially wetted pellet conditions. in this context, a collection of data relative to the wetting efficiency, liquid hold-up and pressure drop measured under high pressure/high temperature has been compiled from the Literature concerning the trickle flow regime in undiluted and diluted beds of catalysts and fines. This useful data provided sufficient and pertinent information to practically implement and successfully validate the model.