Acid-catalytic 1,3-butadiene condensation with para-quinones followed by the obtained product oxidation may be performed in one stage as one-pot process, if assisted by the aqueous solutions of Mo-V-P heteropoly acids with a composition of H_aP_zMo_yV_xO_b. 1,4-naphthoquinone condensation with 1,3-butadiene in the HPA solutions with no organic solvents yields 9,10-anthraquinone (AQ) mixed with tetrahydro-AQ (THA) and dihydro-AQ (DHA). However, AQ yield and its purity may be considerably improved by using water-mixable organic solvents, e.g., acetone, 1,4-dioxane, as well as high vanadium content HPA such as H₁₅P₄Mo₁₈V₇O₈₉ and H₁₇P₃Mo₁₆V₁₀O₈₉. Process optimization provides 70% yield of reaction product containing no less than 90% AQ.