A method for cleaning diesel engine exhaust gas is described. The exhaust gas is passed over a catalytic converter with an active material which contains (% by weight) 70-95% TiO2, 2-10% WO3 and/or MoO3, 0.1-5% V2O5, 0.1-8% CaO, 0.1-8% Al2O3, 0.1-5% B2O3 and 0.1-10% SiO2. A reducing agent for a reduction of nitrogen oxides is metered into the exhaust-gas stream upstream of the catalytic converter.