A modified catalyst, a phosphoric acid fuel cell, and a process for preparing the modified catalyst are provided. The modified catalyst includes a particle of metal-doped porous material and an acid group with a phosphate group, wherein the particle of metal-doped porous material is a particle of porous carrier with metal microparticles attached to a surface thereof, and the acid group with the phosphate group is bonded to the surface of the porous carrier. Since the acid group has the phosphate group, the acid group on the surface of the porous carrier can serve as a proton conduction path while increasing the hydrophilicity of the catalyst to achieve the effect of increasing the adsorption of phosphoric acid. |