Spongy plate-type Raney nickel catalysts for use as hydrogen electrodes of fuel cell were prepared by a new method. In this method, molten aluminum was sprayed on both sides of a spongy plate of nickel as substrate with a plasma flame gun. Then, the spongy nickel electrodes were activated by alloying at a given temperature from 550 to 750°C, and leaching the aluminum from the alloy in alkaline solution. This type of catalyst showed good thermal and electrical conductivity and also mechanical strength by itself. Its polarization resistance was very low, and the characteristics of the electrodes improved with increasing the temperature of heat- treatment for alloying. A constant-potential electrolysis technique was found to be applicable to determination of the hydrogen content of a plate-type Raney nickel catalyst. The hydrogen was anodically removed in a definite amount according to the potential applied. Relationship among the hydrogen content, the BET surface area, and the activity for acetone hydrogenation were also investigated for the case of electrolytic removal. Though the catalyst that partly or completely lost its original hydrogen was able to resorb a considerable amount of hydrogen, it had no relation to the activity for acetone hydrogenation. The ratio for atoms existing in the catalyst could be estimated to be H_ads : H_abs : Ni : Al = 2: 22 : 22 : 1. The complex impedance plot of the Raney nickel electrode suggested that the diffusion step of dissolved hydrogen was relatively slow at the reversible hydrogen electrode in a potassium hydroxide solution. Analytical and morphological studies using SEM, EPMA and XPS were conducted on plate-type Raney nickel catalyst. XPS spectra of Raney nickel catalyst showed that NiO and Ni₂O₃ Or Ni(OH)₂ were formed on the surface, whereas Al₂O₃ or Al₂O₃∙nH₂O were distributed evenly in the vertical direction.