Laboratory-scale experiments were carried out to study the performance of sequencing batch anaerobic reactors (SBAR) with respect to substrate removal and biogas production using a synthetic high-strength organic wastewater. The fill:react ratios and the cycle periods of SBAR were varied to study their effects on SBAR performance. The settleability of SBAR microorganisms was tested. Maximum soluble substrate removal of 73% was observed in the SBAR operating with a cycle period of 16 days and a fill:react ratio of 1:3. For a particular cycle period, the fill period was observed to influence the SBAR performance more than the fill:react ratio. Quasi-second order substrate removal kinetics were developed which could describe the SBAR performance satisfactorily.