2012 World Junior Championships in Athletics – Men's 400 metres
The men's 400 metres at the 2012 World Junior Championships in Athletics will be held at the Estadi Olímpic Lluís Companys on 10, 11, and 12 July.
Medalists
Records
, the existing world junior and championship records were as follows.| World Junior Record | 43.87 | Seoul, South Korea | 28 September 1988 | |
| Championship Record | 44.66 | Santiago, Chile | 20 October 2000 | |
| World Junior Leading | 44.45 | Hengelo, Netherlands | 27 May 2012 |
Results
Heats
Qualification: The first 2 of each heat and the 8 fastest times qualified| Rank | Heat | Lane | Name | Nationality | Time | Note |
| 1 | 6 | 8 | Arman Hall | 46.13 | Q | |
| 2 | 1 | 5 | Boniface Ontuga Mweresa | 46.16 | Q | |
| 2 | 7 | 5 | Steven Solomon | 46.16 | Q | |
| 4 | 4 | 3 | Alphas Leken Kishoyian | 46.22 | Q | |
| 5 | 6 | 7 | Mateo Ružic | 46.30 | Q, PB | |
| 6 | 5 | 5 | Javon Francis | 46.31 | Q, PB | |
| 6 | 6 | 3 | Michele Tricca | 46.31 | q, SB | |
| 8 | 5 | 2 | Luguelín Santos | 46.34 | Q | |
| 9 | 8 | 4 | Aldrich Bailey | 46.40 | Q | |
| 10 | 7 | 4 | Julio Arenas | 46.42 | Q, PB | |
| 11 | 7 | 3 | José Meléndez | 46.45 | q, PB | |
| 12 | 2 | 6 | Machel Cedenio | 46.58 | Q | |
| 13 | 5 | 7 | Andrew Whyte | 46.62 | q, PB | |
| 14 | 2 | 5 | O'Jay Ferguson | 46.69 | Q | |
| 15 | 8 | 8 | Pieter Conradie | 46.70 | Q | |
| 16 | 6 | 4 | Daniel Gyasi | 46.85 | q, PB | |
| 17 | 1 | 2 | Patryk Dobek | 46.90 | Q | |
| 18 | 3 | 2 | Stephan James | 46.99 | Q, NJ | |
| 18 | 5 | 6 | Sorin Vatamanu | 46.99 | q | |
| 20 | 4 | 9 | Jarryd Buchan | 47.04 | Q | |
| 21 | 8 | 5 | Basheer Atiah Al Barakati | 47.07 | q, PB | |
| 22 | 1 | 6 | Marco Lorenzi | 47.19 | q | |
| 23 | 8 | 3 | Nikita Vesnin | 47.22 | q | |
| 24 | 7 | 8 | Lennox Williams | 47.31 | ||
| 25 | 3 | 8 | Nikita Uglov | 47.37 | Q | |
| 25 | 7 | 9 | Rafał Smoleń | 47.37 | ||
| 27 | 8 | 2 | Shaquille Dill | 47.38 | ||
| 28 | 1 | 4 | Sondre Nyvold Lid | 47.40 | ||
| 29 | 1 | 7 | Talbert Poleon | 47.45 | ||
| 30 | 3 | 7 | Diego Palomeque | 47.55 | ||
| 31 | 4 | 6 | Ruan Greyling | 47.65 | ||
| 32 | 4 | 8 | Bandar Atiyah Kaabi | 47.79 | ||
| 33 | 6 | 6 | Luis Alonso Murillo | 47.85 | ||
| 34 | 5 | 3 | Lucka Raherindrainy | 47.90 | PB | |
| 35 | 7 | 2 | Asa Guevara | 47.93 | ||
| 36 | 3 | 5 | Kazushi Kimura | 47.98 | ||
| 37 | 8 | 1 | Oleksiy Pozdnyakov | 48.00 | ||
| 38 | 5 | 1 | Kenta Kimura | 48.03 | ||
| 38 | 6 | 9 | José Ricardo Jiménez | 48.03 | ||
| 40 | 3 | 3 | Benjamin Ayesu-Attah | 48.08 | ||
| 41 | 3 | 9 | Roy Ravana | 48.17 | ||
| 42 | 6 | 2 | Elroy McBride | 48.18 | ||
| 43 | 5 | 9 | Dávid Bartha | 48.32 | ||
| 44 | 1 | 8 | Marc-André Alexandre | 48.37 | ||
| 45 | 2 | 7 | Jani Koskela | 48.46 | ||
| 46 | 8 | 9 | Kwame Donyinah | 48.55 | ||
| 47 | 2 | 4 | Chin Hui Ng | 48.56 | ||
| 48 | 1 | 9 | Alexander Rohani | 48.59 | ||
| 49 | 4 | 7 | Alexandru Babian | 48.63 | ||
| 50 | 1 | 3 | Sumit Malik | 48.82 | ||
| 50 | 4 | 5 | Miloš Raovic | 48.82 | ||
| 52 | 5 | 4 | Victor Soares | 48.93 | ||
| 52 | 8 | 6 | Brandon Valentine-Parris | 48.93 | PB | |
| 54 | 4 | 4 | Lucas Bua | 48.94 | ||
| 55 | 2 | 3 | Mohamedine Mahamadou | 49.05 | ||
| 56 | 2 | 2 | D. Madushanka Ranasinghearachchilage | 49.43 | ||
| 57 | 2 | 8 | José Fernando Martínez | 49.71 | ||
| 58 | 5 | 8 | Marcio Cruz | 50.77 | PB | |
| 59 | 7 | 7 | Abdelkhedere Abdelrahaman Abdelbassit | 50.80 | PB | |
| 60 | 3 | 4 | Mohammed Al Shueili | 51.04 | ||
| 6 | 5 | John Rivan | ||||
| 7 | 6 | Andreas Roth | ||||
| 2 | 9 | Sadam Suliman Koumi | ||||
| 3 | 6 | Mohamed Belbachir | ||||
| 4 | 2 | Madunta Chukwuma | ||||
| 8 | 7 | Gedeon Tshimanga Mutombo |
Semi-Final
Qualification: The first 2 of each heat and the 2 fastest times qualified| Rank | Heat | Lane | Name | Nationality | Time | Note |
| 1 | 3 | 4 | Aldrich Bailey | 45.79 | Q | |
| 2 | 1 | 7 | Luguelín Santos | 45.98 | Q | |
| 3 | 3 | 5 | Javon Francis | 46.06 | Q, PB | |
| 4 | 1 | 4 | Steven Solomon | 46.07 | Q | |
| 5 | 3 | 5 | Boniface Ontuga Mweresa | 46.20 | q | |
| 6 | 2 | 4 | Arman Hall | 46.42 | Q | |
| 7 | 1 | 6 | Alphas Leken Kishoyian | 46.46 | q | |
| 8 | 1 | 8 | Nikita Uglov | 46.49 | q | |
| 9 | 3 | 2 | Patryk Dobek | 46.56 | ||
| 10 | 2 | 6 | Machel Cedenio | 46.59 | Q | |
| 11 | 2 | 2 | Andrew Whyte | 46.81 | ||
| 12 | 3 | 9 | Jarryd Buchan | 46.81 | PB | |
| 13 | 2 | 8 | José Meléndez | 46.83 | ||
| 14 | 2 | 9 | Pieter Conradie | 46.87 | ||
| 15 | 1 | 9 | Michele Tricca | 46.92 | ||
| 16 | 2 | 7 | O'Jay Ferguson | 47.02 | ||
| 17 | 3 | 6 | Marco Lorenzi | 47.25 | ||
| 18 | 2 | 5 | Stephan James | 47.35 | ||
| 19 | 1 | 5 | Mateo Ružic | 47.46 | ||
| 20 | 1 | 3 | Basheer Atiah Al Barakati | 47.48 | ||
| 21 | 3 | 4 | Daniel Gyasi | 47.78 | ||
| 22 | 2 | 3 | Nikita Vesnin | 48.02 | ||
| 23 | 1 | 2 | Sorin Vatamanu | 48.15 | ||
| 24 | 3 | 4 | Julio Arenas | 50.00 |
Final
| Rank | Lane | Name | Nationality | Time | Note |
| 6 | Luguelín Santos | 44.85 | |||
| 4 | Arman Hall | 45.39 | PB | ||
| 8 | Steven Solomon | 45.52 | PB | ||
| 5 | Aldrich Bailey | 45.52 | |||
| 5 | 9 | Machel Cedenio | 46.17 | ||
| 6 | 1 | Alphas Leken Kishoyian | 46.19 | ||
| 7 | 3 | Boniface Ontuga Mweresa | 46.50 | ||
| 8 | 2 | Nikita Uglov | 46.61 | ||
| 9 | 7 | Javon Francis | 47.57 |