The aim of this paper was to assess the suitability of red seaweed Palmaria palmata to be degraded in methane and and the effect of a wide range of thermal and thermo-chemical treatments on anaerobic digestion. Anaerobic digestion of raw and pretreated macro-algae was carried out in batch mesophilic biomethane potential tests. Maceration was carried out at 20°C and thermal treatment in the 70-200°C temperature range. For thermo-chemical pretreatments, NaOH and HCl were respectively added at doses of 0.04 and 0.02 g per g of total solids. The red seaweed Palmaria palmata could be considered as a promising substrate for anaerobic digestion as it presents a high metahne potential (308 9 mL/gVS ). Maceration and thermal treatment at 70°C-120°C had no effect on Palmaria palmata methane potential and higher temperature pretreatments were detrimental. Thermal treatments were associated with high COD solubilisation and, at a high temperature, with the conversion of carbohydrates into soluble recalcitrant compounds. The addition of 0.02 gHCl/gTS or 0.04 gNaOH/gTS had no positive effect at 160°C. The use of 0.04 gNaOH/gTS was beneficial mainly at 20 and 70°C where Palmaria palmata methane potential was increased up to 365 10 mL/gVS. NaOH addition led to higher protein solubilisation yields and the release of mineral nitrogen was favored at a high temperature.