The influence of the incorporation of Ca2+ into MgV2O6, Mg2V2O7 and Mg3V2O8 on the catalytic activities for the oxidative dehydrogenation of propane and the mobility of lattice oxygen in those catalysts has been investigated. On Mg2V2O7 and Mg3V2O8 incorporated with Ca2+, the selectivity to propylene evidently increased with increasing the content of Ca2+ in those catalysts. A decrease of the conversion of propane was observed on Ca2+-added Mg2V2O7 with increasing Ca2+-content; while on Ca2+-added Mg3V2O8, no dependence on the Ca2+-content was observed. The incorporation of Ca2+ was rather insensitive to both the selectivity and the conversion on Ca2+-added MgV2O6. In order to examine the mobility of lattice oxygen in those catalysts, those catalysts were employed for the oxidative dehydrogenation in the absence of oxygen for 2.25 h, followed by the addition of gaseous oxygen into the feedstream. After the addition of gaseous oxygen under the present conditions, oxygen in the effluent was detected at 9, 3.5 and 2 min with Mg2V2O7 incorporated with Ca2+ at these Ca/(Mg + Ca) ratios: 0, 0.05 and 0.1. The times were 1.4, 2 and 4 min with Mg3V2O8 incorporated with Ca2+ as Mg2V2O7. However, no oxygen was detected with MgV2O6 incorporated with Ca2+ even 15 min after the addition of the gaseous oxygen. The present results reveal that the mobility of the lattice oxygen in those catalysts is strongly influenced by the amount of Ca2+ incorporated, resulting in significant effects on the activities for the oxidative dehydrogenation of propane. V-51 MAS NMR was also employed for the observation of redox behaviors of vanadium species in those catalysts during the reaction. (C) 2004 Elsevier B.V. All rights reserved.