The pressure gradient, total liquid hold-up and overall mass transfer capacity for non-foaming co-current upward flow of oxygen/water and oxygen/1 M NaOH through a bed of graphite felt were measured as part of a study of multiphase fluid dynamics in three-dimensional electrodes. Tests were done at 17-25 degrees C in a bed of compressed graphite felt 356 mm long, by 38 mm wide by 3 mm thick, with 22 mu m fibres and 90 +/- 2% porosity. For co-current flow, lengthwise (i.e.axial) and upward through the bed, with gas loads 0 < G < 0.4 kg/m(2) s, together with liquid loads 1.5 < L < 7.3 kg/m2 s, the pressure gradient and total liquid hold-up ranged, respectively, from about 0.2 to 2 bar/m, and from 0.44 to 1. Similarly, for gas loads 0.04 < G < 0.36 kg/m(2) s, together with liquid loads 3 < L < 7.6 kg/m(2) s, the overall (gas to solid) mass transfer capacity ranged from 3 to 9 s(-1). The pressure gradient, total liquid hold-up and mass transfer capacity are correlated by dimensional interpolation formulas, as a function of the mass velocities of the liquid and the gas through the fibre bed.