Abstract: Process of manufacture, and method of use of a carrier-supported catalyst with transition metal phthalocyanines for the oxidizing treatment of exhaust gases which gases contain volatile compounds containing oxygen and/or nitrogen, which catalyst can be obtained by charging a carrier with at least one transition metal phthalocyanine and activation of the charged carrier with (i) a gas mixture which contains nitrogen oxide and/or oxygen, at temperatures between room temperature and 500.degree. C., or with (ii) a solution which contains nitric acid and/or an oxidation agent.