| Regimental number | 94 |
| Place of birth | Branxholm, Tasmania |
| School | Branxholm State School, Tasmania |
| Religion | Church of England |
| Occupation | Miner |
| Address | Branxholm, Tasmania |
| Marital status | Single |
| Age at embarkation | 19 |
| Next of kin | Father, George Claxton O'Brien, Branxholm, Tasmania |
| Enlistment date | |
| Rank on enlistment | Private |
| Unit name | 40th Battalion, Machine Gun Section |
| AWM Embarkation Roll number | 23/57/1 |
| Embarkation details | Unit embarked from Hobart, Tasmania, on board HMAT A35 Berrima on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 40th Battalion |
| Fate | Killed in Action |
| Place of death or wounding | Messines, Belgium |
| Age at death | 19.3 |
| Age at death from cemetery records | 19 |
| Place of burial | Bethlehem Farm West Cemetery (Row A, Grave No. 10), Messiness, Belgium |
| Panel number, Roll of Honour, Australian War Memorial | 133 |
| Miscellaneous information from cemetery records | Parents: George and Genevieve O'Brien, Branxholm, Tasmania. Native of Launceston, Tasmania |
| Family/military connections | Brother: 1603 Harold Douglas O'BRIEN, 9th Bn, killed in action, 22 July 1916. |
| Other details |
War service: Western Front Medals: British War Medal, Victory Medal |