An oxidation catalyst for treating an exhaust gas produced by a compression ignition engine comprising: a substrate; a catalytic material disposed on the substrate, wherein the catalytic material comprises platinum (Pt); and a region comprising a capture material, wherein the capture material comprises a Pt-alloying metal disposed or supported on a refractory oxide, wherein the refractory oxide comprises at least 65% by weight of zirconia, wherein the region is arranged to contact the exhaust gas after the exhaust gas has contacted and/or passed through the catalytic material.