The compounds CU2ZnSnX4 and Cu2SnX3 (X = S or Se) are promising semiconductor materials for thin film photovoltaic applications. Based on a crystallographic growth model we derive the solid-state reactions for these four compounds starting from the binary sulphides and selenides of copper, zinc and tin. Exploiting these predicted solid-state reactions which are promoted by epitaxial relations between the educts will result in fast formation reactions as preferred in technical processes. The direct formation of Cu2ZnSnX4 is concurring with a two-step process in which Cu2SnX3 occurs as an intermediate product. (C) 2006 Elsevier B.V. All fights reserved.