The liquid-phase dehydration of glycerol to acrolein over PO4/Nb205 catalysts was performed to investigate the effect of various amounts of PO4 supported and the regeneration of used catalysts on catalytic performance. The amount of acid sites and strength of the surface acidity increased with the amount of PO4 supported. Thus, these results seem to suggest that the amount of produced acrolein in the dehydration of glycerol is relatively influenced by the surface acidity of the catalysts used. Catalytic activity was restored by burning out of the surface deposited carbons in the used PO4/Nb205 catalysts at 500 C in air. However, it was not completely restored after regeneration for the 50 wt% PO4/Nb205 catalyst due to the incomplete recovery of the drastically reduced surface acidity by the loss of the much resolved PO4 during the reaction. 2013 Elsevier B.V. All rights reserved.