Process for the preparation of a polymer containing benzohetero[1,3]diazole. units which comprises reacting at least one disubstituted benzohetero[1,3]diazole compound with at least one heteroaryl compound. Said polymer can be advantageously used in the construction of photovoltaic devices such as, for example, photovoltaic cells, photovoltaic modules, solar cells, solar modules, on both a rigid and flexible support. Furthermore, said polymer can be advantageously used in the construction of Organic Thin Film Transistors (OTFTs), or of Organic Field Effect Transistors (OFETs).