Energy recovery from lignocellulosic solid marine wastes, Posidonia oceanica wastes (POW) with slow pyrolysis responds to the growing trend of alternative energies as well as waste management. Physicochemical, thermogravimetric (TG/DTG) and spectroscopic (FTIR) characterizations of POW were performed. POW were first converted by pyrolysis at different temperatures (450 degrees C, 500 degrees C, 550 degrees C and 600 degrees C) using a fixed-bed reactor. The obtained products (bio-oil, syngas and bio char) were analyzed. Since the bio-oil yield obtained from POW pyrolysis is low (2 wt.%), waste frying oil (WFO) was added as a co-substrate in order to improve of biofuels production. The co-pyrolysis gave a better yield of liquid organic fraction (37 wt.%) as well as syngas (CH4, H-2...) with a calorific value around 20 MJ/kg. The stoichiometric models of both pyrolysis and co-pyrolysis reactions were performed according to the biomass formula: C alpha H beta O gamma N delta S epsilon. The thermal kinetic decomposition of solids was validated through linearized Arrhenius model. (C) 2016 Elsevier Ltd. All rights reserved.