| Regimental number | 2089 |
| Place of birth | Petersburg South Australia |
| Other Names | John Juston |
| Religion | Roman Catholic |
| Occupation | Postal employee |
| Address | Woodville, South Australia |
| Marital status | Single |
| Age at embarkation | 23 |
| Next of kin | Mother, Mrs Susan O'Leary, Russel Street, Woodville, South Australia |
| Enlistment date | |
| Date of enlistment from Nominal Roll | |
| Rank on enlistment | Private |
| Unit name | 32nd Battalion, 3rd Reinforcement |
| AWM Embarkation Roll number | 23/49/2 |
| Embarkation details | Unit embarked from Adelaide, South Australia, on board HMAT A28 Miltiades on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 32nd Battalion |
| Fate | Killed in Action |
| Place of burial | Messines Ridge British Cemetery (Plot I, Row A, Grave No. 12), Belgium |
| Panel number, Roll of Honour, Australian War Memorial | 121 |
| Family/military connections | Brother: 1941 Pte Emmet O'LEARY, 22nd Bn, killed in action, 9 March 1918; Cousin (1st): 2087 Pte Humphrey O'LEARY, 32nd Bn, killed in action, 20 July 1916. |
| Other details |
War service: Western Front Medals: British War Medal, Victory Medal |