Engine Room Hooch was an alcoholic beverage produced clandestinely by members of Starfleet in stills. Engine Room Hooch was most often produced on board starships, but would at times be produced in other Starfleet installations as well. Much like engine room stew, the hooch was usually by a member or members of the engineering department. In the 2250s century various officers on a number of different ships produced Engine Room Hooch. The production of Engine Room Hooch was officially frowned upon by Starfleet, but in actual practice a blind eye was often turned to the production of the beverage as many senior officers would themselves partake of the beverage.
In his Starfleet Academy days, Montgomery Scott and a number of other students produced Engine Room Hooch in a generator room at the academy. It was believed that the superintendent of the academy knew about the still, but tolerated the presence of the still because he enjoyed the beverage himself from time to time.
Shortly after being posted to the USS Enterprise, Lieutenant Scott began producing Engine Room Hooch. He located his still near the warp core. The beverage became very popular, Number One commented that the hooch was better than that of the Lionheart's. Shortly after production was begun, a dilithium crystal cracked, which bombarded the still with gamma radiation, and contaminated the beverage produced within. It resulted in the alcohol being very potent, a couple drinks resulted in extreme intoxication.
As a result, the still and the bottles were confiscated and destroyed. Chief Engineer Caitlin Barry announced that production of Engine Room Hooch would no longer be tolerated.