| Game |
| Result | Moves |
Year |
Event/Locale | Opening |
| 1. K O'Riordan vs J Sadlier |
| 1-0 | 22 |
1965 |
IRL-ch | D99 Grunfeld Defense, Smyslov |
| 2. J Moles vs K O'Riordan |
| 1-0 | 25 |
1966 |
IRL-ch | B49 Sicilian, Taimanov Variation |
| 3. A Dennehy vs K O'Riordan |
| 1-0 | 31 |
1967 |
IRL-ch | C97 Ruy Lopez, Closed, Chigorin |
| 4. K O'Riordan vs W Heidenfeld |
| 0-1 | 32 |
1967 |
IRL-ch | A85 Dutch, with c4 & Nc3 |
| 5. Suttles vs K O'Riordan |
| 1-0 | 45 |
1968 |
Lugano | A00 Uncommon Opening |
| 6. G Koshnitsky vs K O'Riordan |
| 1-0 | 30 |
1968 |
Lugano Olympiad | A98 Dutch, Ilyin-Genevsky Variation with Qc2 |
| 7. K O'Riordan vs N Ornithopoulos |
| ½-½ | 20 |
1968 |
Lugano Olympiad | A56 Benoni Defense |
| 8. G Budowski vs K O'Riordan |
| 1-0 | 25 |
1968 |
Lugano Olympiad | C08 French, Tarrasch, Open, 4.ed ed |
| 9. K O'Riordan vs A Nejjar |
| ½-½ | 24 |
1968 |
Lugano Olympiad | E56 Nimzo-Indian, 4.e3, Main line with 7...Nc6 |
| 10. P Svedenborg vs K O'Riordan |
| ½-½ | 24 |
1968 |
Lugano Olympiad | C12 French, McCutcheon |
| 11. G Barcza vs K O'Riordan |
| 1-0 | 22 |
1968 |
Lugano Olympiad | A04 Reti Opening |
| 12. K O'Riordan vs A Magrin |
| 0-1 | 32 |
1968 |
Lugano Olympiad | E14 Queen's Indian |
| 13. K O'Riordan vs J Santos |
| 1-0 | 38 |
1968 |
Lugano Olympiad | D37 Queen's Gambit Declined |
| 14. K O'Riordan vs R Quesada Jr |
| 0-1 | 31 |
1968 |
Lugano | B70 Sicilian, Dragon Variation |
| 15. K O'Riordan vs A Colon |
| 1-0 | 39 |
1968 |
Lugano Olympiad | B33 Sicilian |
| 16. K O'Riordan vs V Riego |
| 0-1 | 41 |
1968 |
Lugano Olympiad | B82 Sicilian, Scheveningen |
| 17. K O'Riordan vs J Moles |
| ½-½ | 17 |
1971 |
IRL-ch | E61 King's Indian |