The recent publication of Rim et al. (2013) on layer inversion in three-phase fluidized beds is extended by further exploration of the liquid inversion velocity and examination of the corresponding liquid holdup. In conjunction with an empirical equation of Han in al. (1990) for three-phase liquid holdup, as modified for binary solids, the two-phase layer inversion model of jean and Fan (1986) yields surprisingly good predictions when applied to three-phase fluidization, even though it fails for the limiting case of U-g=0. (c) 2014 Elsevier Ltd. All rights reserved,