We apply a two-fluid model to investigate hydrodynamic differences in a three-dimensional fluidized bed operating at pressures of 1, 2, 4, 8, 16, 20, and 32 bar. The simulation results are compared with experimental results from the literature and show very good agreement. A detailed investigation is carried out on pressure fluctuations, porosity distribution, and bubble and solids flow characteristics. At high pressure, the porosity distribution is homogeneous and fluidization is smooth. The bubble size depends upon the location in the 3D bed, showing different trends at different pressures. The average bubble size is reduced with an increase in pressure, caused by a difference in coalescence and splitting of bubbles. An initial increase in pressure from 1 to 2 bar shows an increase in bubble rise velocity, but a further increase in pressure causes bubbles to rise more slowly. High up-flow of solids is observed in the center at high pressures, with pronounced differences in solids circulation vortices.