This paper presents the application techniques in the fluid catalytic cracking unit (FCCU) to reduce the SO₂ emissions based on the maximum limit value of 550 mg/Nm³ put forward by European environmental regulations. Under normal operating conditions, the FCCU generates 2800 mg/Nm³ SO₂ when it processes a heavy feed that contains up to 1.92 wt.% sulfur. The SO₂ emissions produced in the FCCU regenerator was monitored and evaluated using a wet scrubbing system (WSS) in which NaOH or other scrubbing liquids consumption is requisite. SOx reduction additives were incorporated in the WSS to reduce the caustic consumption by the wet gas scrubber for overall reduction of refinery operational expenses (OPEX). Utilization of WSS was able to reach up to 96.4% SO₂ reduction. From the industrial testing, it was demonstrated that the addition of 5.3 wt.% SOx additive into the FCC fresh catalyst decreased the SO₂ by 45%, up to 1525 mg/Nm³. Consequently, the WSS caustic consumption was reduced by 2390 kg/day, representing a 45% reduction in initial consumption. Based on the industrial results, a model was proposed to assist refineries evaluate the economic benefits of incorporating WSS and SOx additive technologies for exhaust gas emission reduction. The model demonstrates an overall OPEX reduction of up to 495,000 USD/year, depending on the market price for NaOH, additives and sulfur.