Porous sulphur-doped carbons have been prepared by using polythiophene (PTh) as carbon precursor and KOH as activating agent. The activation process was carried out under several operating conditions, i.e. a KOH/PTh weight ratio of 2 or 4 and reaction temperatures in the 600–850°C range. The porous carbons thus obtained exhibit very large apparent surface areas and high pore volumes of up to 3000m 2 g −1 and 1.75cm 3 g −1 respectively for a sample prepared at 850°C and with a KOH/PTh weight ratio=2. The pore size distribution of these carbons gradually changes with the reaction temperature. Thus, whereas the porosity of the samples prepared at 600°C is mostly formed by micropores ∼1nm, those obtained at 850°C exhibit two pore systems with diameters of ∼1nm and ∼2.5nm. These polythiophene-based porous carbons have large sulphur contents in the 3–12wt% range, and this percentage decreases as the reaction temperature rises. The sulphur present in these carbons forms two types of functional groups (i.e. sulphide –C–S–C– and sulphone –C–SO 2 –C–) which act as bridges between adjacent aromatic rings.