| Game |
| Result | Moves |
Year |
Event/Locale | Opening |
| 1. L Shamkovich vs T Thorhallsson |
| 1-0 | 28 |
1984 |
It (open) | A96 Dutch, Classical Variation |
| 2. T Bjornsson vs T Thorhallsson |
| 0-1 | 36 |
1984 |
It (open) | C50 Giuoco Piano |
| 3. W Arencibia vs T Thorhallsson |
| ½-½ | 61 |
1986 |
Wch U20 | D31 Queen's Gambit Declined |
| 4. Anand vs T Thorhallsson |
| 1-0 | 39 |
1986 |
Gausdal | B57 Sicilian |
| 5. T Thorhallsson vs Blatny |
| ½-½ | 31 |
1986 |
Gausdal | C56 Two Knights |
| 6. Blatny vs T Thorhallsson |
| 1-0 | 40 |
1986 |
Gausdal | B01 Scandinavian |
| 7. T Thorhallsson vs Fedorowicz |
| 0-1 | 24 |
1987 |
London Lloyds (10) | B22 Sicilian, Alapin |
| 8. T Thorhallsson vs Hertneck |
| 0-1 | 48 |
1987 |
Gausdal Int | C10 French |
| 9. Ivanchuk vs T Thorhallsson |
| 1-0 | 37 |
1987 |
Baguio City | D43 Queen's Gambit Declined Semi-Slav |
| 10. T Thorhallsson vs Flear |
| 1-0 | 61 |
1987 |
London (England) | C54 Giuoco Piano |
| 11. Anand vs T Thorhallsson |
| 1-0 | 43 |
1987 |
London | C04 French, Tarrasch, Guimard Main line |
| 12. T Thorhallsson vs Blatny |
| 0-1 | 56 |
1987 |
Baguio City | C60 Ruy Lopez |
| 13. T Thorhallsson vs Browne |
| ½-½ | 65 |
1988 |
It (open) | A04 Reti Opening |
| 14. T Thorhallsson vs Browne |
 | 1-0 | 51 |
1988 |
It ( shv. ) | B99 Sicilian, Najdorf, 7...Be7 Main line |
| 15. Petursson vs T Thorhallsson |
| 0-1 | 49 |
1988 |
Reykjavik cq | A13 English |
| 16. T Thorhallsson vs Van Wely |
| ½-½ | 32 |
1988 |
EU-chJ U20 Arnhem | B81 Sicilian, Scheveningen, Keres Attack |
| 17. T Thorhallsson vs Christiansen |
| 1-0 | 37 |
1988 |
Reykjavik op | B99 Sicilian, Najdorf, 7...Be7 Main line |
| 18. Kotronias vs T Thorhallsson |
| 1-0 | 61 |
1988 |
It ( shv. ) | B01 Scandinavian |
| 19. T Thorhallsson vs Polugaevsky |
| 0-1 | 47 |
1988 |
It (open) | B90 Sicilian, Najdorf |
| 20. T Thorhallsson vs Christiansen |
| 1-0 | 51 |
1988 |
It (open) | B40 Sicilian |
| 21. Adams vs T Thorhallsson |
 | 1-0 | 23 |
1988 |
EU-chJ U20 Arnhem | B01 Scandinavian |
| 22. T Thorhallsson vs Polugaevsky |
 | 1-0 | 18 |
1988 |
It (open) | B12 Caro-Kann Defense |
| 23. T Thorhallsson vs Petursson |
| 1-0 | 35 |
1989 |
Iceland | B25 Sicilian, Closed |
| 24. Gelfand vs T Thorhallsson |
| 0-1 | 48 |
1989 |
EU-ch U21 | D49 Queen's Gambit Declined Semi-Slav, Meran |
| 25. J Benjamin vs T Thorhallsson |
| 1-0 | 31 |
1990 |
Reykjavik (Iceland) | B01 Scandinavian |