NOVELTY - Preparing a benzodithiophene compound comprises reacting at least one monohalogenated dithiophene compound with at least one internal alkyne.    USE - The process is useful for preparing benzodithiophene compound (claimed). The benzodithiophene compound is useful in the construction of photovoltaic devices such as, for example, photovoltaic cells, photovoltaic modules, solar cells, solar modules, on both rigid and flexible supports. It can be advantageously used as spectrum converter in luminescent solar concentrators (LSC); and as precursor of monomeric units in the preparation of semiconductor polymers.    ADVANTAGE - The process provides the following advantages: (a) reduction of the number of synthesis steps with a relative reduction in the processing times and in the process costs; (b) use of monohalogenated starting products generally more economical and more stable than the corresponding dihalogenated compounds; (c) use of more economical and more stable internal alkynes with respect to diboron esters of internal alkenes; (d) greater safety conditions (e.g. absence of corrosive and/or flammable reagents such as, for example, titanium tetrachloride, lithium diisopropylamide (LDA)) for both the health of the operators and from an environmental point of view; and (e) relatively short reaction temperatures and times thus avoiding the possible degradation of the product obtained and higher process costs.    DETAILED DESCRIPTION - Preparing a benzodithiophene compound having general formula (I) comprises reacting at least one monohalogenated dithiophene compound having general formula (II) with at least one internal alkyne having general formula of -R1-triple bond-R2- (III).    A, B, C, D, E and F=independently selected from a sulfur atom; or a group C-R3;    R3=a hydrogen atom, a linear or branched 1-20C alkyl group, a cycloalkyl group optionally substituted, an aryl group optionally substituted, a heteroaryl group optionally substituted, a linear or branched 1-20C alkoxyl group, a group -CHO, a carboxyl group -COOR4;    R4=a linear or branched 1-20C alkyl group, an amide group -CONHR4 or -CON(R4)2, provided that one of A, B and C and one of D, E, and F, represents a sulfur atom; E represents a sulfur atom only in the case in which B represents a sulfur atom; when E and B represent a sulfur atom, D represents a group C-R3, where R3 is different from hydrogen; the sum of the double carbon-carbon bonds present in the two thiophene rings and in the benzene ring is equal to 5;    R1 and R2=independently selected from a hydrogen atom, a linear or branched 1-20C alkyl group, a cycloalkyl group optionally substituted, an aryl group optionally substituted, a heteroaryl group optionally substituted; and    X=a halogen atom selected from chlorine, bromine, and iodine.