On the basis of a large data bank consisting of more than 2600 experimental results published for cocurrent upflow fixed-bed reactors, a state-of-the-art correlation for the prediction of external liquid saturation was proposed. The correlation relied upon combination of dimensional analysis and artificial neural networks which allowed identification of six most expressive dimensionless groups. Robustness of proposed correlation was assessed by testing it on a huge test data file, and the limitations of the literature correlations with regard to their generalization capabilities were demonstrated.