The rapid development of anaerobic digestion brought with it the problem of biomass resources and supply. Marine biomass is emerging as an advantageous substrate. Such macroalgae as Palmaria palmata are promising substrates for anaerobic digestion as they possess a high methane potential (308 +/- 9 mL gvs(-1)). The aim of this paper was to study the efficiency of the anaerobic digestion of P. palmata after a range of thermal and chemical pretreatment. The anaerobic digestion of raw and pretreated macroalgae was carried out in batch mesophilic biomethane potential tests (BMP). Thermal (between 20 and 200 degrees C) and thermo-chemical (addition of NaOH and HCl) pretreatment were performed on P. palmata. Thermal pretreatments at 20, 70, 85 and 120 degrees C and acid or soda pretreatments at 160 degrees C had no significant effect on P. palmata's methane potential. After high temperature pretreatment (180-200 degrees C), the BMP decreased with the temperature which can be explained by the formation of refractory compounds in the liquid fraction. In contrast, the addition of 0.04 gNaOH gTS(-1) at 20 degrees C led to a release of proteins and induced an increase in the BMP from 308 +/- 9 mL gvs(-1) (untreated) to 365 +/- 9 mL gvs(-1). Thus, P. palmata can be used advantageously as a substrate for anaerobic digestion and its methane production enhanced by the addition of NaOH. (C) 2013 Elsevier B.V. All rights reserved.