Novel magnetic semiconductor compounds in the ternary system II-IV-V-2 with the 3d transition element Mn have been prepared. The use of alternative growth methods for CdGeP2:-Mn and ZnGeP2-Mn quasi-binary systems proved the existence of material in both polycrystalline and single crystal forms. The prepared compounds share the chalcopyrite crystal structure and reveal ferromagnetic behavior over a wide temperature range. The Curie temperature has been measured for CdMnGeP2 as 320 K (single crystal) and 310 K (polycrystalline bulk). (C) 2002 Elsevier Science B.V. All rights reserved.