Vanadium oxide supported on zirconia and modified with MoO₃ was prepared by adding Zr(OH)₄ powder into a mixed aqueous solution of ammonium metavanadate and ammonium molybdate followed by drying and calcining at high temperatures. The spectroscopic studies of prepared catalysts were performed using FTIR and Raman spectroscopies, solid-state ⁵¹V NMR spectroscopy, and X-ray differaction (XRD). In the case of calcination at 773 K, for samples containing a low loading V₂O₅ (below 15 wt%), vanadium oxide was obtained in a highly dispersed state; for samples containing a high loading V₂O₅ (equal to or above 15 wt%), vanadium oxide crystallized well because the V₂O₅ loading exceeded the formation of a monolayer on the surface of ZrO₂. The experimental results indicate that the presence of MoO₃ and V₂O₅ retards the crystallization of the zirconia and stabilizes the tetragonal ZrO₂ phase. The ZrV₂O₇ and Zr(MoO₄)₂ compounds were formed through the reaction of V₂O₅ and ZrO₂ or MoO₃ and ZrO₂ at 873 K and these compounds decomposed into V₂O₅, MoO₃, and ZrO₂ at high temperatures. The high catalytic activity of the V₂O₅-MoO₃/ZrO₂ catalyst calcined at 973 K was probably due to the formation of the Zr(MoO₄)₂ phase, which was responsible for the high electrical conductivity. Catalytic tests for 2-propanol dehydration and cumene dealkylation indicated that the addition of MoO₃ and V₂O₅ to ZrO₂ enhanced both the catalytic activity and the acidity of the V₂O₅-MoO_{3/ZrO2 catalysts.}