A process for the preparation of tetraselenotetracene chlorides or bromides of formula I, ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently of one another H or F; R.sub.1 is CH.sub.3 and R.sub.2, R.sub.3 and R.sub.4 are H; R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each CH.sub.3 ; or R.sub.1 and R.sub.2 are CH.sub.3 or Cl, and R.sub.3 and R.sub.4 are H, and X is Cl or Br, which process includes reacting a tetraselenotetracene of formula II ##STR2## in a polar aprotic solvent, with stoichiometric amounts of an ammonium hydrochloride or hydrobromide, in the presence of oxygen at elevated temperature. An organic binder may be dissolved in the reaction solution and a substrate coated with this solution. After evaporation of the solvent, electrically conductive coatings are obtained that consist of a network of crystal needles of compounds of formula I in the binder matrix.