| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 1. W Heidenfeld vs R W O'Brien |
| 1-0 | 36 | 1964 | IRL-ch | B12 Caro-Kann Defense |
| 2. W H Pratten vs R W O'Brien |
| 1-0 | 24 | 1965 | Stevenson Memorial | B10 Caro-Kann |
| 3. Karpov vs R W O'Brien |
| 1-0 | 34 | 1972 | Karpov Simul, 26b London | B81 Sicilian, Scheveningen, Keres Attack |
| 4. R W O'Brien vs M J Hall |
| 1-0 | 50 | 1972 | Islington Open | A00 Uncommon Opening |
| 5. R W O'Brien vs N Littlewood |
| 0-1 | 42 | 1972 | Islington Open | A00 Uncommon Opening |
| 6. M Macdonald-Ross vs R W O'Brien |
| 0-1 | 45 | 1973 | GRE Islington Open | A06 Reti Opening |
| 7. R W O'Brien vs Keene |
| 0-1 | 30 | 1974 | Hammersmith Open | B06 Robatsch |
| 8. Chandler vs R W O'Brien |
| 1-0 | 40 | 1976 | Max Fuller Elo Tournament | C40 King's Knight Opening |
| 9. R Emerson vs R W O'Brien |
| 1-0 | 40 | 1977 | 1st Lloyds Bank Masters Open | B33 Sicilian |
| 10. Keene vs R W O'Brien |
| 1-0 | 45 | 1981 | 5th Lloyds Bank Masters Open | E49 Nimzo-Indian, 4.e3, Botvinnik System |
| 11. R W O'Brien vs S Shutler |
| 0-1 | 29 | 1981 | 5th Lloyds Bank Masters Open | B33 Sicilian |
| 12. R W O'Brien vs D I Patrick |
| 0-1 | 24 | 1981 | Lewisham International | C68 Ruy Lopez, Exchange |
| 13. G Iskov vs R W O'Brien |
| 1-0 | 26 | 1981 | Lewisham International | B12 Caro-Kann Defense |
| 14. R W O'Brien vs H Ha'eri Zadeh |
| ½-½ | 16 | 1981 | Lewisham International | C69 Ruy Lopez, Exchange, Gligoric Variation |
| 15. I Gelfer vs R W O'Brien |
| 1-0 | 37 | 1981 | Lewisham International | A31 English, Symmetrical, Benoni Formation |
| 16. B Leverett vs R W O'Brien |
| 1-0 | 33 | 1981 | Lewisham International | E46 Nimzo-Indian |
| 17. D King vs R W O'Brien |
| 1-0 | 29 | 1981 | Regency Masters | C40 King's Knight Opening |
| 18. R W O'Brien vs G Flear |
| 0-1 | 101 | 1981 | Regency Masters | C54 Giuoco Piano |
| 19. G de Boer vs R W O'Brien |
| 1-0 | 44 | 1981 | Regency Masters | A16 English |
| 20. A L Hosking vs R W O'Brien |
| 0-1 | 41 | 1981 | Regency Masters | B14 Caro-Kann, Panov-Botvinnik Attack |
| 21. R W O'Brien vs R Nokes |
| 0-1 | 45 | 1981 | Regency Masters | B06 Robatsch |
| 22. R J Woodcraft vs R W O'Brien |
| ½-½ | 19 | 1981 | Regency Masters | B30 Sicilian |
| 23. R W O'Brien vs A Roll |
| ½-½ | 18 | 1981 | Regency Masters | C00 French Defense |
| 24. E Schiller vs R W O'Brien |
| ½-½ | 56 | 1981 | Regency Masters | D34 Queen's Gambit Declined, Tarrasch |
| 25. R W O'Brien vs A Dunnington |
| 0-1 | 65 | 1981 | Regency Masters | D30 Queen's Gambit Declined |
Kibitzing
