Bubble column slurry reactors are widely used in industry. Often in practice, high catalyst loadings are used, and the liquid phase is usually an organic liquid. Literature correlations are not reliable enough for commercial scale up. In this paper, we develop a scale-up procedure that relies on the use of computational fluid dynamics (CFD), with Eulerian descriptions of the gas and slurry phases. Interactions between the bubbles and the slurry are taken into account by means of a momentum exchange, or drag. coefficient; this coefficient is estimated from the experimental measurements of gas holdup in a column of 0.051 m diameter. The turbulence in the slurry phase is described using the k-epsilon model. The CFD model is first validated by comparison with the measured gas holdup data for a range of superficial gas velocities. The validated CFD model is then used to simulate the hydrodynamics of a column of 1 m diameter. The CFD simulations clearly demonstrate the strong influence of scale on the column hydrodynamics. (C) 2003 Elsevier Science B.V All rights reserved.