In a process of manufacturing a sintered electrode for use in a voltaic cell, which electrode has fine and coarse pores, which process comprises
- reducing an iron(III) oxide powder having a particle size not in excess of 10 micrometers to form iron powder granules having fine pores and having a particle size not in excess of 500 micrometers,
- compacting said iron powder granules to form an electrode body, and
- sintering said electrode body at a sintering temperature up to 750.degree. C. under a reducing atmosphere,
- the improvement comprising
- reducing said iron oxide powder at a temperature of 600.degree. to 800.degree. C. to form an agglomerated iron powder,
- deriving said iron powder granules from said agglomerated iron powder and mixing said granules with an organic solid expanding agent adapted to be volatilized at said sintering temperature, and
- compacting the resulting mixture of iron powder granules and expanding agent to form said electrode body.