Electrode paste composition

The invention provides an electrode paste composition that enables a sufficient pore volume of electrode for high generating performance while maintaining good storage stability. The paste composition comprises a carbon black supporting a hydrogen reduction catalyst, an electrolyte, an organic solvent having a boiling point of 100 to 200°C, a water-soluble organic solvent having a boiling point of less than 100°C, and optionally one or more components selected from a dispersant, a carbon fiber and water.