Together they wrote:
* Novels:
* The Real Charlotte (1894)
* The Silver Fox (1903)
* Some Experiences of an Irish R.M. (1906)
* Further Experiences of an Irish R.M. (1908)
* In Mr. Knox's Country (1915)
* Dan Russel the Fox (1921)
* The Big House (1925)
* The Irish R.M. in Peace and War (1930)
* Short Story Collections:
* All on the Irish Shore (1903)
* The Irish R.M. (1906)
* The Mount Eagle Letters (1928)
* More Stories of an Irish R.M. (1932)
* Plays:
* The Other Man's Wife (1924)
* The Man who Missed the Boat (1926)
* An Irish Gentleman (1931)
They were also known for their humorous and satirical depictions of Irish society. Their most famous work is probably the series of stories featuring "The Irish R.M.", which depicts the comical adventures of an English magistrate in rural Ireland.
It's worth noting that E. Ø. Somerville also published several novels and short stories under her own name, but these are less well-known than her collaborations with Martin Ross.