The dairy industry in Brazil generated in 2014 around 88.5 billion litters of effluent, the fatty residue, separated in the treatment of this effluent, currently lacks treatment.Anaerobic digestion is a treatment option from which it is possible, among other things, to obtain biogas, a renewable source of energy, which represents an important alternative to fix the country's energy matrix.However, lipid residues form sludges that are difficult to manage and decompose into long chain fatty acids (LCFAs) that are inhibitory to methanogenic microorganisms.As a strategy to effectively treat this residue, we evaluated an anaerobic co-digestion system employing fatty residues from a fat box of a dairy plant, and sugarcane bagasse pre-treated under sub and supercritical CO2 conditions: (i) 40°C / 70 bar (ii) 60ºC / 200 bar and (iii) 80°C / 200 bar, with and without addition of NaOH respectively.Of this pre-treatments, stood out the one with CO2 at 60˚C and 200 bar by which was achieved the removal of 8.07% of lignin.The methanogenic production from the anaerobic digestion of sugarcane bagasse was increased in all cases in which the material was pre-treated with sub and supercritical CO2, with the exception to the cases in which high temperatures and NaOH were combined.The residues from the dairy fat box showed high methanogenic potential in the concentration range evaluated and no inhibition was verified.The co-digestion of the greasy residues and the sugarcane bagasse with and without pre-treatment, did not present advantage in compare to the mono-digestion of the materials.