Hydrodynamic characteristics of a new mode of liquid-solid fluidization, termed as 'inverse fluidization' in which low density floating particles are fluidized with downward flow of liquid, are experimentally investigated. The experiments are carried out with low density particles (< 534 kg/m 3 ) which allow high liquid throughputs in the system. During the operation, three regimes, namely, packed, semi-fluidization and fully fluidization are encountered. Empirical correlations are proposed to predict the pressure drop in each regime. A computational procedure is developed to simulate the variation of pressure drop with liquid velocity.