Anaerobic digestion is a biochemical process that occurs naturally in the absence of oxygen. It is used commonly in developing countries to produce both energy and biofertilizers. Objective: The purpose of this work was to study the anaerobic digestion of green macroalgae (Ulva lactuca and Codium tomentosum), which cause severe environmental problems in Dakar-Senegal, and elsewhere along Africa's Atlantic coast. Methodology and Results: These green macroalgae were characterized in terms of physicochemical properties and biochemical methane potential (BMP). Their characteristics were compared to those of other locally available feedstock, such as cow manure and Jatropha curcas cake. The results showed that volatile solids of macroalgae were about 500 g VS/kg and twice that of cow manure. Furthermore, the methane potential of macroalgae was twice (216.4 L CH4/kg VS) that of cow manure (100.3 L CH4/kg VS). The green macroalgae achieved a heating value potential of 2151 kWh/t VS. The methane potential of Jatropha cake as a substrate for anaerobic digestion was intermediate (133.6 L CH4/kg VS) but contained a large quantity of lignin (34%), a slowly biodegradable organic substance. Conclusions and application of findings: This study results showed that green macroalgae could be used as a substrate for the production of renewable energy the biogas in Senegal.