A new practically wasteless method of synthesis of high-vanadium Mo-V-phosphoric heteropoly acids aqueous solutions having modified composition HaPzMoyVx'Ob (HPA-x'(zP)) has been developed. These solutions are used as thermally stable catalysts of oxidation of organic compounds with O-2. At the first stage of the synthesis, V2O5 is dissolved in the cooled H2O2 to form peroxy vanadium compounds, which spontaneously decompose to yield H6V10O28 Solution. The latter is stabilized by addition of an excess of H3PO4. The prepared (H9PV14O42 + H3PO4) Solution is added to a gradually evaporating suspension of (MoO3 + H3PO4) to form the HPA-x'(zP) solution. The catalysts based on HPA-x'(zP) solutions do not yield V-containing deposits up to 170 degrees C. Syntheses of HPA-x'(zP) solutions can be realized both in a lab and pilot scale. (c) 2008 Elsevier B.V. All rights reserved.