| Game |
| Result | Moves |
Year |
Event/Locale | Opening |
| 1. H Mertens vs T Cmiel |
| ½-½ | 9 |
2003 |
NRW Class1 0304 | B42 Sicilian, Kan |
| 2. H Mertens vs G Borgo |
| ½-½ | 105 |
2010 |
31st Crespi Memorial | C41 Philidor Defense |
| 3. H Mertens vs M Tratar |
| 0-1 | 37 |
2010 |
31st Crespi Memorial | A07 King's Indian Attack |
| 4. S Drazic vs H Mertens |
| 0-1 | 51 |
2010 |
31st Crespi Memorial | A45 Queen's Pawn Game |
| 5. H Mertens vs R Martinez |
| 1-0 | 32 |
2010 |
31st Crespi Memorial | B67 Sicilian, Richter-Rauzer Attack, 7...a6 Defense, 8...Bd7 |
| 6. A Dranov vs H Mertens |
| ½-½ | 10 |
2011 |
82nd German Chess Championship | D14 Queen's Gambit Declined Slav, Exchange Variation |
| 7. H Mertens vs S Siebrecht |
| 0-1 | 38 |
2011 |
82nd German Chess Championship | B42 Sicilian, Kan |
| 8. H Mertens vs H Poetsch |
| ½-½ | 32 |
2011 |
82nd German Chess Championship | B00 Uncommon King's Pawn Opening |
| 9. U Krause vs H Mertens |
| 0-1 | 63 |
2011 |
82nd German Chess Championship | B33 Sicilian |
| 10. V Lederle vs H Mertens |
| 0-1 | 34 |
2011 |
82nd German Chess Championship | B42 Sicilian, Kan |
| 11. H Mertens vs N Huschenbeth |
| 0-1 | 69 |
2011 |
82nd German Chess Championship | B90 Sicilian, Najdorf |
| 12. H Mertens vs M Molinaroli |
| 0-1 | 34 |
2011 |
82nd German Chess Championship | E62 King's Indian, Fianchetto |
| 13. R Buhmann vs H Mertens |
| ½-½ | 29 |
2011 |
82nd German Chess Championship | A04 Reti Opening |
| 14. O Mueller vs H Mertens |
| ½-½ | 17 |
2011 |
82nd German Chess Championship | B07 Pirc |
| 15. H Mertens vs I Cheparinov |
| 0-1 | 77 |
2012 |
Reykjavik Open | B93 Sicilian, Najdorf, 6.f4 |
| 16. M Ornolfsson vs H Mertens |
| ½-½ | 47 |
2012 |
Reykjavik Open | C05 French, Tarrasch |
| 17. H Mertens vs E Forsa |
| 1-0 | 33 |
2012 |
Reykjavik Open | A18 English, Mikenas-Carls |
| 18. H Mertens vs B Bjornsson |
| 1-0 | 40 |
2012 |
Reykjavik Open | C77 Ruy Lopez |
| 19. J Ragnarsson vs H Mertens |
| ½-½ | 70 |
2012 |
Reykjavik Open | A65 Benoni, 6.e4 |
| 20. S Sigurjonsson vs H Mertens |
| 0-1 | 70 |
2012 |
Reykjavik Open | B21 Sicilian, 2.f4 and 2.d4 |
| 21. E De Winter vs H Mertens |
| 0-1 | 38 |
2012 |
Reykjavik Open | A21 English |
| 22. H Mertens vs P Lasinskas |
| 0-1 | 56 |
2012 |
Reykjavik Open | C41 Philidor Defense |