Different tungsten oxide catalysts supported on chlorinated activated carbons were prepared by using ammonium tungstate and tungsten pentaethoxide as precursor compounds. The supported catalysts were pretreated in wet air at 623 K for 6 h and characterized by N-2 adsorption at 77 K, temperature-programmed desorption, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The results indicate that tungsten oxide is anchored to chlorine surface complexes through the formation of W-Cl bonds during either the preparation or wet air pretreatment of the catalysts. This has a major influence on the particle size and distribution of the metal oxide phase supported on the carbon particles.