A simple theoretical model is used to describe hydrodynamic behaviour in bubble columns. The model is based on an energy balance which takes into account the energy dissipation in the liquid motion and the energy dissipation at the gas-liquid interface. Gas hold-up, liquid velocity at the column axis and radial profile of liquid velocity are predicted in a wide range of operating conditions (J(G) up to 1.452 m s(-1)) and column sizes (D = 0.1-1 m and H = 1.22-9.5 m) with good accuracy. Predictions of liquid velocity are also compared with one of the most widely accepted models.