In the present study, the effect of biofuel and nano biofuel on the performance of a domestic boiler was investigated and compared with those emitted during the burning of diesel fuel. The biofuel was produced from waste cooking oil using Potassium hydroxide (KOH) as a catalyst. Carbon Nanotubes (CNT) with different concentrations of 0.05% /L, 0.1% /L, 0.15% /L, 0.2% /L, and 0.25% /L were added to the produced Biodiesel to form a nano biofuel that was used to power a domestic boiler for demonstration purposes. The obtained performance results were compared using the same boiler when operating with biofuel and nano biofuel, respectively. When operated with different CNT concentrations, the emitted species from the boiler were also investigated by sampling the exhaust gases in each studied case. This study revealed that the boiler's performance when operated with CNT was enhanced by decreasing the toxic emitted gasses and increasing the outlet water temperature compared to the case of the boiler with the biofuel alone. It increased the outlet water temperature and decreased NOx (ppm) emissions.