Abstract: For use particularly with exhaust systems from cooking areas, such as roof-mounted restaurant exhaust fans, a grease catch basin is mountable about the exhaust duct so as to collect condensed or precipitated grease from exhaust system parts lying above the catch basin, typically an exhaust fan and housing. Such condensed or precipitated grease flows or drips into the catch basin surrounding the duct. The catch basin is of sheet aluminum, and typically is mounted about the conventional roof curb through which the exhaust duct extends. A solvent reservoir is mounted in the upper part of the grease catch basin, and contains a solvent for breaking down grease. Solvent passes from the reservoir into the catch basin preferably via a rope wick extending through the bottom of the solvent reservoir into the catch basin. Wicking action can be controlled by controlling the compression of the rope wick. The catch basin is open-topped, such that rain water also can fall into the catch basin.