Thirsty Merc's debut studio album was the self-titled Thirsty Merc, released on 16 August 2004. The band again chose to work with Warner Music Australia. The album spent 48 weeks on the ARIA Albums Chart, peaking at #15, and launched the band in the Australian mainstream. The album reached #29 on New Zealand's RIANZ chart. The band worked with producer Lindsay Gravina on the album, who had been producing Australian bands over the past 15 years or so, notably The Living End and Magic Dirt. The band's debut was entirely recorded and mixed on 2 inch tape, and mixed by Gravina himself at his Melbourne studio, Birdland Studios.
Five singles were released from Thirsty Merc: "Emancipate Myself", "My Completeness", "Someday, Someday", "In the Summertime", and "When the Weather Is Fine". All of the singles charted in Australia, with "Someday, Someday" reaching #19, while only "In the Summertime" charted in New Zealand, where it peaked higher than in Australia. "In the Summertime" was nominated for the 2005 ARIA Award for "Best Video", while "Someday, Someday" was nominated for "Single Of The Year", "Best Group", and "Best Pop Release".
In interviews after the album's release, Thistlethwayte stated that the album was the band trying to "Just be yourself", and that the album was "just about being young and living in Australia".