| Regimental number | 1425 |
| Place of birth | Tumut, New South Wales |
| Place of birth | Adelong, New South Wales |
| School | Xavier Catholic College, Melbourne, Victoria |
| Religion | Roman Catholic |
| Occupation | Farmer |
| Address | Tumut, New South Wales |
| Marital status | Married |
| Age at embarkation | 23 |
| Next of kin | Wife, Mrs. Leila Olga O'Brien, Strathmore, 143 Victoria Street, Pott's Point, Sydney, New South Wales |
| Previous military service | nil |
| Enlistment date | |
| Rank on enlistment | Private |
| Unit name | 6th Light Horse Regiment, 11th Reinforcement |
| AWM Embarkation Roll number | 10/11/3 |
| Embarkation details | Unit embarked from Sydney, New South Wales, on board HMAT SS Hawkes Bay on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 6th Light Horse Regiment |
| Fate | Died of wounds |
| Place of death or wounding | Amman, Palestine |
| Age at death | 26 |
| Age at death from cemetery records | 26 |
| Place of burial | Damascus British War Cemetery (Row C, Grave No. 29), Syria |
| Panel number, Roll of Honour, Australian War Memorial | 5 |
| Miscellaneous information from cemetery records | Parents: William and Jane O'BRIEN; husband of Leila O'BRIEN, Gilmore Hotel, Tumut, New south Wales |
| Family/military connections | Brother: [Orlando ?] J. O'Brien, killed at Messines, Belgium in June 1917. |