This paper describes catalytic investigations into soot oxidation over KOH, K 2 CO 3 ,KNO 3 ,CH 3 COOK and K 2 SO 4 doped iron and manganese spinels. For Fe 3 O 4 it was found that alkali doping (0.5 monolayer) is con fi ned to the surface and results in the substantial enhancement of its catalytic activity ( Δ T 50% ≈ 80 °C for K 2 CO 3 ), depending on the precursor nature. For Mn 3 O 4 K-doping at low loading (0.5 ML) has a negative effect, whereas at high loading (9 ML) leads to the formation of a birnessite shell on the Mn 3 O 4 core catalyst with a spectacular increase of the soot oxidation rate ( Δ T 50% ≈ 150 °C).