A phenomenological model based on the generalization of the single-phase Forchheimer equation was recently proposed for predicting pressure drop and phase saturations in gas-liquid co-current horizontal and downward high-pressure packed beds. Here, we extend the model to packed-bubble (co-current upflow) and trickle-bed operation using phase saturation power laws similar to Corey relative permeabilities. The power-law exponents were fitted using a wide pressure gradient and liquid saturation databank in co-current up/downward packed-bed flows. It was found that this approach, as well as other in the literature developed for down-flow reactors apply also to upward flows; the prediction accuracy was comparable for both flow directions to existing literature approaches. (C) 2004 Society of Chemical Industry.