Oxidation of propene to acetone and butene-1 to butanone in aqueous solutions was studied in the presence of homogeneous catalysts Pd+HPA-x (HPA-x=H3+xPVxMo12-xO40 having Keggin composition, x=1-4). The reaction order with respect to alkenes is 1, to palladium is 0.5 for propene and 0.66 for butene-1, respectively. The rate of alkene oxidation does not depend on concentration of HPA-x and acidity of catalyst solution. Alkenes are also successfully oxidized in the presence of new catalysts Pd + HPA-x' containing modified high-vanadium non-Keggin HPA-x' (x'> 4). The HPA-x' solutions have improved thermal stability and are very promising for oxidation of the lower alkenes. Kinetic peculiarities of oxidation of both alkenes in the presence of solutions of HPA-x' and HPA-x are similar. (c) 2006 Elsevier B.V. All rights reserved.