The invention relates to a semiconducting polymer and a method of preparing a semiconducting polymer. The polymer in accordance with the invention has the repeating unit (--A--NH--B--S--), wherein A and B are conjugated groups. The polymer proves to be readily soluble already in customary organic solvents, without the groups A and B having been provided with saturated substituents, and, after doping, has an electric conductivity of approximately 1 S/cm. The method yields semiconducting polymers in accordance with the invention, which have a high molecular weight and few topological defects.