The discharge of dye effluent from textile manufacturing has the potential to induce detrimental impacts on the environment and human health. The removal of dye is a crucial environmental concern prior to the discharge of wastewater. Coagulation process is commonly used method to treat dyeing effluent. However, coagulation process involves large amount of chemical consumption. Hence, process optimisation is required to reduce the chemical consumption. The primary aim of this research was to optimize the removal of Congo red (CR) dye through response surface methodology (RSM) using polyaluminum chloride (PACl) and ferric chloride (FeCl3) coagulants. The evaluation of the impact of pH and coagulant dose on dye removal was conducted to determine the appropriate range of parameters for use in RSM for the purpose of optimising the process. Applying RSM in the optimization of the coagulation process resulted in the determination of optimal conditions. These conditions include a dosage of 39.4 mg/L of PAC at an initial pH of 6.3, as well as a dosage of 46.8 mg/L of FeCl3 at an initial pH of 8.4. The implementation of RSM facilitated the identification of the true optimal condition, leading to a significant reduction in the amount of chemical coagulants required for colour removal.