The paper presents results of studies directed towards the production of monograin powders of CuInSe2 for possible use in solar cells preparation. The results concern the tailoring of chemical and defect composition of materials, development of the technology of manufacturing monograin layers (MGL) on the base of developed materials and the cleaning of open surfaces of the grains in the MGL by different mechanical, chemical and electrochemical methods. It is shown that up to now the low efficiency of MGL solar cells is associated with the chemical and defect composition of the monograin powder materials and with difficulties in cleaning the surfaces of the crystals in the MGL before depositing active contacts. (C) 2003 Elsevier Science B.V. All rights reserved.