The goal of this study was to assess the effect of different modes of operation and configurations of Anaerobic Sequencing Batch Reactors (ASBRs) treating phenolic wastewater. Several lab-scale reactors were used in the mesophilic range. The reactors were fed with synthetic wastewater with a COD of 5 g/L using phenol as a carbon source (variable concentration) and glucose as a co-substrate. One and two-phase (hydrolytic/acidogenic-methanogenic) systems in batch and fed-batch operation were evaluated. The one-stage reactor operated by the fed batch (which was the only configuration using phenol as a sole carbon source), presented better results for the removal of phenol, reaching 100% removal in 10 days at a concentration of 210 mg/L. The two-stage configuration had removal percentages near 100%, but the methanogenic reactor presented greater degradation of the remaining phenol not removed in the hydrolytic/acidogenic reactor. ASBRs might be a feasible alternative to treat this type of effluent due to their operational flexibility.