As will be discussed below in further detail, the noble metal oxide is applied onto the tin oxide particles via pH-initiated precipitation of noble metal species, followed by thermal treatment at high temperature. By this method, a catalyst composition is typically obtained which has a BET surface area being lower than the BET surface area of the non-coated tin oxide starting material. Accordingly, for providing a catalyst composition having a BET surface area of from 5 to 95 m²/g, a tin oxide (either doped or non-doped) having a slightly higher BET surface area is typically subjected to the noble metal oxide deposition treatment. The tin oxide starting material can have a BET surface area of e.g. from 10 m²/g to 100 m²/g.

As indicated above, each of the tin oxide particles is at least partially coated by a noble metal oxide layer, wherein the noble metal oxide is an iridium oxide or an iridium-ruthenium oxide.

The formation of a noble metal oxide layer on the tin oxide particles even at relatively low amounts of noble metal (instead of forming isolated oxide particles being distributed over the support surface) results from applying the preparation method as described below (i.e. pH-induced precipitation from an aqueous medium, followed by calcination at high temperature). The presence of a noble metal oxide coating layer on a tin oxide particle assists in improving electrical conductivity of the catalyst composition, which in turn improves electron transfer efficiency during the catalytic reaction. For obtaining an electrical conductivity of at least 7 S/cm, a noble metal oxide layer which is partially coating the carrier particle can be sufficient. However, in the present invention, it is also possible that the tin oxide particles are completely coated by the noble metal oxide layer.