The paper presents the efficiency of nitrogen removal from wastewater using molasses as an external carbon source. The study was conducted during the municipal wastewater treatment process in two independent activated sludge chambers of SBR type. One of the chambers contained molasses as the source of easily available organic compounds. The study showed that the use of molasses as the external carbon source during wastewater treatment resulted in a higher efficiency of nitrogen removal than in the reactor where it no support using external carbon source was applied at the same time resulting low level of the COD value in the treated wastewater.