The present invention relates to a process for the preparation of benzodithiophene compounds which comprises reacting a derivative of 3,3′-bithiophene with at least one internal alkyne. Said benzodithiophene compounds can be suitably functionalized and polymerized to give electron-donor compounds which can be used in photovoltaic devices such as, for example, photovoltaic cells, photovoltaic modules, solar cells, solar modules, on both rigid and flexible supports. Furthermore said benzodithiophene compounds can be advantageously used as spectrum converter in luminescent solar concentrators (LSCs). Said benzodithiophene compound can also be advantageously used as precursor of monomeric units in the preparation of semiconductor polymers.