In this study, biogas production was investigated in mesophilic conditions from sugar beet pulp (SBP). In untreated conditions, water dissolution rate was 15.5% and biogas production rate was 168.7 mL/g TS (total solid). Alkaline thermal pretreatments were applied at 100 degrees C with 3 N NaOH and KOH solutions. Amounts of alkaline and acid were added in an amount equal to 5%, 10%, 15%, 20%, and 30% of the solids in the reactor. Acid thermal pretreatments were applied at 100 degrees C with 5% (v/v) H2SO4 and HNO3 solutions. The anaerobic digestion (AD) time was shortened by approximately 10 days after pretreatment. The highest biogas yield was 458.4 mL/g TS as a result of KOH thermal pretreatment. In this reactor, soluble chemical oxygen demand (sCOD) removal was 87.1%, and cellulose, hemicellulose, and lignin removals were 32.4%, 28.6%, and 33.5% w/w, respectively. It was observed that the cumulative biogas production (CBP) successfully fitted the modified Richards (MR) model and modified Gompertz (MG) model.