In an espresso-style extraction hot water (90 +/- 5 degrees C) is driven through a coffee packed bed by a pressure gradient to extract soluble material from the coffee matrix. Permeability is a key parameter affecting extraction as it determines the flow rate through the bed and hence brewing and residence time. This may alter bed-to-cup mass transfer and therefore impact brew quality. In this work a methodology that will allow estimation of the permeability of coffee packed beds in steady-state was developed. Fitting measured flow rate - pressure drop data to Darcy's law resulted in permeability values in the range of 10(-13)-10(-14) m(2). m Disagreement between the experimental and theoretical permeability, as estimated from dry measurements of particle size distribution and Kozeny-Carman equation, was found. Bed consolidation may have a larger effect on the packing structure than the mere decrease in bed bulk porosity. The Kozeny-Carman equation, corrected with a porositydependent tortuosity according to a power law, gave a good fit of the data. (C) 2014 The Authors. Published by Elsevier Ltd.