The anaerobic treatment of phenolic wastewater has demonstrated to be a suitable biological system, for that reason, a large number of systems have been implemented in a lab/pilot scale, several industrial plants have also been developed. Despite of this, there is a lack of modeling applications within these systems. In order to enhance the anaerobic treatment of this kind of water, a simplified model of 2 populations and 3 reactions was developed and implemented. The parameter calibration and the model validation were carried out with experimental data obtained from an Anaerobic Sequencing Batch Reactor treating phenolic wastewater through two different operational strategies: sequential batches with a co-substrate and sequential fed-batches without a co-substrate. The model predicted the reactors performance accurately for the different experimental conditions tested. Therefore, the theoretical basis of the model is, in general terms, valid, and its utilization to predict the reactors performance or in control purposes is feasible.