Abstract: New catalysts are described which are useful over a wide temperature range for purifying exhaust gases from internal combustion engines burning gasoline. The new catalysts are of composite form comprising a water-gas type catalyst and at least one platinum group metal such as platinum, palladium or ruthenium. As water-gas catalyst, use can be made of a mixture or iron oxide and chromium oxide. By using such composite catalysts on a common refractory substrate, nitrogen oxides, carbon monoxide and unburnt hydrocarbons can be removed to a substantial degree in a single stage.