We produced Mn-doped InAsP in metal-organic vapor phase epitaxy (MOVPE) grown InAsR Good quality samples could be only prepared by heteroepitaxy on InP(0 0 1), while layers on GaAs showed very little smoothing after the initial roughening. The samples were characterized by X-ray diffraction, photoluminescence and Hall effect measurements. By varying the As content from 0% to 70% the ionization energy of the Mn-acceptor level varied from 220 to < 30meV and drops into the valence band for higher concentrations. (C) 2008 Elsevier B.V. All rights reserved.