Monitoring of methane (CH4) and carbon dioxide (CO2) in biogas from different feed-stocks using superluminescent diode (SLED) is proposed and demonstrated. The SLED has a broadband spectrum (1540 nm–1640 nm) and this allows for the detection of CO2 at 1570 nm and CH4 at 1600 nm range simultaneously. Experiments were performed on biogas collected from various biomass like food waste, sewage waste and cattle dung. CO2 and CH4 concentration levels were monitored on each source of biogas. The etalon based sensing system provides the opportunity to select absorption lines with a low resolution spectrometer. Further, measurements on CH4 and CO2 concentration changes depending on the food-waste input to the plant are demonstrated. © 2017 Elsevier B.V.