This paper presents a correlation for estimating the pressure drop of single-phase flow inside ceramic and metal sponges (open celled-foams) based on easily available geometrical parameters. These could be the specific surface area (per unit volume), the mean cell diameter or the mean strut and window diameters of a sponge type. The correlation was derived from own experimental values using 16 different ceramic sponges. Due to its non-dimensional form, the correlation can be applied to different fluids. The pressure drop correlation was validated including more than 2500 experimental values reported by about 20 authors for nearly 100 different sponge samples. Concluding from the validation, the correlation is valid within the range of 10(-1) < Re < 10(5) (Re=Reynolds number based on the hydraulic diameter). The wide range of Reynolds numbers offers the possibility to design equipment for common technical applications. (C) 2012 Elsevier Ltd. All rights reserved.