Patent ID: 7335619

Claim:
A catalyst for the fuel electrode of a solid polymer fuel cell, wherein the catalyst comprises fine precious metal particles loaded on a support composed of an electrically conductive material, wherein: a weight ratio of said fine precious metal particles and said support composed of an electrically conductive material (fine precious metal particles:electrically conductive material) is 60:40 to 95:5; and said fine precious metal particles satisfy the following conditions (a) to (c): (a) the fine precious metal particles contain platinum and ruthenium, and the mixing ratio thereof (platinum:ruthenium) is within a range between 1:1 and 1:3 in terms of molar ratio; (b) the fine precious metal particles have an average particle diameter of 3 to 10 nm; and (c) the fine precious metal particles contain oxygen, and the weight ratio of the fine precious metal particles and oxygen (fine precious metal particles:oxygen) is 86:14 to 93:7.