p-Type organic semiconductors are attractive to develop new photo- and photoelectro-catalytic systems, particularly if the conduction band is located at negative redox potentials. An easy synthetic route to produce carbon doped carbon nitride (C-n (>) N-3(4)) with a stable p-type semiconducting character was optimized. The precursors used were melamine and triaminopyrimidine. The p-type N-3(4) exhibited a remarkable photoactivity under visible light compared with pristine C3N4, which is a stable n-type organic semiconductor deeply studied as heterogeneous photocatalyst for many environmental applications. The photoelectrochemical features of the synthesized p-type materials and pristine C3N4 were deeply investigated with chronopotentiometry and cyclic voltammetry, in the dark and under different illumination conditions, and then compared with the photo catalytic activity using 2-fluorophenol as substrate and different radiation sources. The p-doping with carbon of C3N4 reduces the band gap, slightly moves the potential of the valence band, and increases the conduction band to more positive potentials, thus precluding the application of these materials when large negative redox potentials are needed.