Production of magnetic alloy particles comprises: (a) preparing a starting material consisting of hydrated iron oxide particles and iron oxide particles, where the starting particles contain 15-45 at.% cobalt; (b) reducing the particles to magnetic alloy particles; (c) passivating the alloy particles in an oxygen-contg. atmosphere at 20-100<o> C; (d) annealing the passivated particles in an inert atmosphere at 120-450<o> C; and (e) further oxidising the annealed alloy particles in an oxygen-contg. atmosphere. Also claimed are the magnetic alloy particles produced.
