Display omitted •Novel Fe/N/C electrocatalysts for ORR in acid media based in iron-containing porous organic polymers from non-expensive dicyanobenzenes (DCB).•1,2-DCB lead to more active catalysts than 1,4-DCB, because vicinal N atoms in 1,2-DCB are more prone to coordinate to one Fe atom as FeNx moieties.•The ORR activity is boosted by the presence of FeNx moieties. In this work, we report the synthesis of Fe/N/C electrocatalysts using triazine based porous organic polymers as precursors. Iron-doped triazine porous organic polymers were obtained by in situ polymerization of iron precursor and 1,2- or 1,4- dicyanobenzene (DCB). In order to obtain the actual catalyst, the polymer obtained was subjected to thermal treatment under NH3. The catalysts obtained exhibit activity and durability for the oxygen reduction reaction in acid electrolyte. Thorough characterization of the catalysts reveal the formation of several types of iron species, including metallic iron, iron carbides and Fe-Nx moieties. The latter species is the main responsible for the high activity measured for the oxygen reduction reaction in acid electrolyte. 1,2-DCB results in more active catalysts than 1,4-DCB due to the higher fraction of FeNx ensembles in the former, probably because vicinal positions of N-bearing groups are more prone to coordinate Fe atoms.