The effect of activation treatments of K-free and K-MoVSbO bronzes on either their physico-chemical characteristics or catalytic properties for propane partial oxidation have been studied. The as-synthesized materials, hydrothermally prepared and presenting (SbO)(2)M20O56 type structure (the so called M1-phase), were activated by different heat-treatments, characterized (XRD, SEM-EDS, HRTEM, V K-edge, Sb L-1- and K-edges XANES, EPR, XPS, NH3-TPD) and tested in propane partial oxidation. In general, the selectivity to acrylic acid (the most valuable product) was higher in K-containing MoVSbO catalysts. In addition, different trend in the catalytic behavior was found between K-free and K-containing MoVSbO series, mostly related to different changes in crystalline phases distribution and catalysts surface characteristics (composition and acid properties) induced by the several activation treatments which also modified the average Sb oxidation state. (C) 2014 Elsevier B.V. All rights reserved.