μ-XAFS analysis using an X-ray μ-beam (1000 nm (h) × 800 nm (v)) was successfully carried out on a single particle of a practical catalyst NiO_x/Ce₂Zr₂O_y (0 ≤ x ≤ 1, 7 ≤ y ≤ 8). The oxidation state and local coordination structure of the NiO_x/Ce₂Zr₂O_y particle were characterized by Ni K-edge μ-XANES and μ-EXAFS, which showed the catalytically active and inactive phases of a single catalyst particle.