The present study has investigated kinetic features of bioconversion of biodiesel-derived crude glycerol to dihydroxyacetone with immobilized Gluconobacter oxydans cells using modified Haldane substrate-inhibition model. The results have been compared against free cells and pure glycerol. Relative variations in the kinetic parameters K-S, K-I, V-max, n and X reveal that immobilized G. oxydans cells (on PU foam substrate) with crude glycerol as substrate give higher order of inhibition (n) and lower maximum reaction velocities (V-max). These results are essentially implications of substrate transport restrictions across immobilization matrix, which causes retention of substrate in the matrix and reduction in fractional available substrate (X) for the cells. This causes reduction in both K-S (substrate concentration at V-max/2) and K-I (inhibition constant) as compared to free cells. For immobilized cells, substrate concentration (S-max) corresponding to V-max is practically same for both pure and crude glycerol as substrate. (C) 2016 Elsevier Ltd. All rights reserved.