•Faster decolorization of AB-14 dye by AO and EC and follow pseudo-first order kinetic.•Faster and similar decolorization by EC and AO due to the generation of strong oxidant OH in the bulk.•Current density (j), Initial dye conc. (Co), NaCl conc. (CN), and pH affect the oxidation efficiency.•Synergy between coagulation and oxidation by OH and active chlorine species. In this study, a laboratory scale for the treatment of a recalcitrant and toxic synthetic wastewater containing diazo dye, acid brown 14 (AB-14) has been comparatively performed by two electro-catalytic treatment processes, namely anodic oxidation (AO) and electrocoagulation (EC) using a new batch electrochemical cell. Additionally, the influence of several operating parameters such as; current density (j), initial dye concentration (Co), NaCl concentration (CN), and pH on the color removal efficiency and chemical oxygen demand (COD) are evaluated. The powerful capability of the AO and EC of AB-14 which related to the mechanistic reaction pathway is shown. The poor degradation is ascribed to higher Co and pH, while the enhancement of j and CN is responsible for better degradation of AB-14 dye. The results indicate that the EC is more effective than AO under the same operational condition. A kinetic model is developed for evaluation of the pseudo-first-order-rate constant (kapp) as a function of various operational parameters. The results emphasize the high efficiency of AO and EC and the clean processes which are hopeful alternative for the treatment of the large volume wastewater of the textile industry.