The combustion of petroleum products with a high heavy metal content results in ash wastes containing considerable amounts of vanadium oxides that can penetrate into the ground under the influence of atmospheric precipitation and poison the ground waters. These wastes and the spent catalysts of the hydrodemetallization process can be a valuable source of vanadium. The paper presents results of tests on the recovery of vanadium compounds from ash waste samples and spent catalysts by means of extraction with aqueous solutions of acids, bases and inorganic salts. The method applied consists of the precalcination of the ashes with potassium hydroxide followed by the water extraction of the forming vanadates, thus recovering 90-97% of the vanadium oxides.