Oil cakes are the main by-product of the oilseeds industry. Their conversion into biomethane by anaerobic digestion was investigated in this work. The effect of acidic thermal-pretreatment was studied on mesophilic in batch anaerobic digestion. Acid pretreatments were carried out in the temperature range of 130 to 210°C, H2SO4 concentration ranged from 0 to 5% (in weight) and time was set to 5 min. For all pre-treated samples the methane production was more important than for untreated sample (195 mLCH4/g VS). The highest productions (302 ± 10 mLCH4/ g VS) were reached for the temperature of 170°C with acid concentration ranging from 1% to 5%. At this temperature, acid concentrations lower than 1% had no significant impact on methane production, in comparison to thermal treatment alone. Moreover, the volume of biogas produced by the soluble fraction increased with severe pretreatments. Indeed for pre-treatments at 170°C, 5% and at 198°C, 4.26%, the production of biogas resulting from the soluble part was respectively of 53% and 57% as against 36% at 142°C, 0.74%.