Abstract: A process for the thermal treatment of an Fe-Co-Cr alloy for a permanent magnet, constituted by weight of 10 to 40% of Cr, from 0 to 10% of one or more elements of the group Al, Nb, Ta, W, Mo, V, Ti, Si and Cu, the remainder being iron. The process comprises homogenization treatment at between 1200.degree. and 1400.degree. C., an annealing treatment and one or more tempering treatments at between 500.degree. and 600.degree. C.; the annealing treatment comprises two stages, the first at between 630.degree. and 670.degree. for 5 to 30 minutes, the second, without a return to ambient temperature, at a temperature of from 40.degree. to 70.degree. C. below the previous stage for at least 10 minutes.Isotropic or anisotropic magnets whose hysteresis curve exhibits a better rectangular shape are thus obtained.