A process for the preparation of electrically conductive polymers, having conductivities greater than 10.sup.-2 S/cm, wherein from 0.1 to 95% by weight of black phosphorus and from 0.5 to 25% by weight of sodium, potassium, rubidium or cesium or of an amide of these, preferably in tetrahydrofuran, dimethoxyglycol, nitromethane or methylene chloride (the molar ratio of alkali metal or amide to organic compound preferably being from 1:1 to 1:5) are added to an organic polymer chosen from the group comprising the polyphenylenes, heteropolyphenylenes and polyacetylenes, in the absence of moisture and of oxygen. The electrically conductive polymers obtained can be used in the electrical industry for the production of solar cells, for conversion and fixing of radiation and for the production of electrical and magnetic switches, and can also be used for the antistatic treatment of plastics.