Magnetic and metallographic investigations are reported on Sm(Co,Cu)z with 5?z<8.5 and Cu‐contents up to 35% of the transition metal fraction. The as‐cast as well as the heat treated materials were evaluated. Two typical compositions Sm(Co0.65Cu0.35)5.6 as an example of a single phase 1:5 type magnet material and Sm(Co0.84Cu0.16)6.9 as an example of a two phase magnet material, namely a primary 2:17 phase in a 1:5 type matrix, are considered in detail. Both materials produced, after an appropriate high temperature annealing, rectangular ideal demagnetization curves, implying that the macroscopic 2:17 primary phase is magnetically hard. Low temperature heat treatments resulted in two maxima in the coercivity IHC as a function of T. The data are discussed based on metallurgical investigations of the phase diagrams and electron microscopy results.