Process for manufacturing chlorine dioxide

A process for manufacturing chlorine dioxide by reducing a chlorate selected from the group consisting of sodium chlorate, potassium chlorate, calcium chlorate and magnesium chlorate, in a strong acid selected from the group consisting of sulfuric acid present in a concentration of from about 0.5 to about 6 moles per liter of reaction medium, hydrochloric acid in a concentration of from about 0.01 to about 4 moles per liter of reaction medium and a mixture thereof, in the presence of a complex catalyst consisting of palladium (II) and a .beta.-diketone of the formula ##STR2## wherein R.sub.1 and R.sub.2 are selected from the group consisting of hydrogen, an alkyl radical having from 1 to 10 carbon atoms and an aryl radical;

• and R.sub.3 and R.sub.4 are selected from the group consisting of hydrogen and a methyl radical.