Activated carbons (ACs) were prepared with pitch as an analogous precursor in the presence of dibenzothiophene (DBT) and were applied as supercapacitor electrode materials. KOH was employed in the activation. The influence of DBT content in the precursor on the pore structure of the resultant AC and its capacitive performance were investigated intensively. The results show that DBT in the precursor can react with the KOH activation agent, thus reducing the actual KOH/char ratio. It is found that the presence of DBT in the precursor not only reduces the pore volume and the specific surface area of the resultant AC but also deteriorates the capacitance and rate capability of the AC electrode. However, of special interest is the fact that no residual sulfur was found in the prepared AC regardless of the DBT content in the precursor.