| Final 16:30 | time | | L | | 1. William Carr |  United States | 46.28s | WR | 4 | | 2. Benjamin Eastman | United States | 46.50s | | 2 | | 3. Alexander Wilson |  CAn Canada | 47.4s | | 3 | | 4. William Walters |  ZAF Siuth Africa | 48.2s | | 1 | | 5. James Gordon | ZAF South Africa | 48.2s | | 5 | | 6. George Golding |  AUS Australia | 48.8s | | 6 |
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| | | Venue: Los Angeles Memorial Coliseum 100,000. 27 competitors from 15 nations. |
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| | | First 3 from each Semi advanced to Final. |
| Semi 1 | time | | | 1. William Carr | United States | 47.2s | Q, OR | | 2. Alexander Wilson | Canada | 47.8s | Q | | 3. George Golding | Australia | 48.0s | Q | | 4. Godfrey Rampling |  Great Britain | 48.0s | | | 5. Felix Rinner |  Austria | 48.8s | | | 6. Joachim Büchner |  Germany | 49.2s | |
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| Semi 2 | time | | | 1. Ben Eastman | United States | 47.6s | Q | | 2. William Walters | South Africa | 48.2s | Q | | 3. James Gordon | United States | 48.2s | Q | | 4. Börje Strandvall |  Finland | 48.4s | | | 5. Crew Stoneley | Great Britain | 48.6s | | | 6. Jimes Ball | Canada | 49.0s | |
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| World record: | Benjamin Eastman | USA | 46.4ys | Palo Alto, United States 26 March 1932 | | Olympic record: | Eric Liddell | GBR | 47.6s | Paris, France 11 July 1924 |
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| Quarter-Finals - Thursday 04.08 16:00 | | First 4 from each Quarter to Semi-Finals. |
| Quarter 1 | time | | | 1. William Carr | United States | 48.4s | Q | | 2. William Walters | South Africa | 48.5s | Q | | 3. George Golding | Australia | 48.6s | Q | | 4. Alexander Wilson | Canada | 49.6s | Q | | 5. Domingos Puglisi |  Brazil | 50.1s | | | 6. Iwao Masuda |  Japan | Unknown | |
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| Quarter 2 | time | | | 1. James Gordon | United States | 48.6s | Q | | 2. Godfrey Rampling | Great Britain | 48.8s | Q | | 3. Joachim Büchner | Germany | 48.9s | Q | | 4. James Ball | Canada | 49.3s | Q | | 5. Hjalle Johannesen |  Norway | 49.4s | | | 6. Seikan Oki | Japan | Unknown | |
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| Quarter 3 | time | | | 1. Ben Eastman | United States | 48.8s | Q | | 2. Felix Rinner | Austria | 48.9s | Q | | 3. Börje Strandvall | Finland | 49.0s | Q | | 4. Crew Stoneley | Great Britain | 49.1s | | | 5. Raymond Lewis | Canada | 49.1s | | | 6. Adolf Metzner | Germany | 49.2s | |
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| Heat 1 | time | | | 1. Adolf Metzner | Germany | 50.4s | Q | | 2. Seikan Oki | Japan | 50.5s | Q | | 3. Alexander Wilson | Canada | 50.5s | Q | | 4. Johan Kell Areskoug |  Sweden | 50.7s | |
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| Heat 2 | time | | | 1. Ben Eastman | United States | 49.0s | Q | | 2. Joachim Büchner | Germany | 49.3s | Q | | 3. Hjalle Johannesen | Norway | 49.5s | Q | | 4. Carlos de Anda |  Mexico | 49.8s | |
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| Heat 3 | time | | | 1. Börje Strandvall | Finland | 49.8s | Q | | 2. James Ball | Canada | 50.0s | Q | | 3. Iwao Masuda | Japan | 50.1s | Q | | 4. Sten Pettersson | Sweden | 50.2s | |
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| Heat 4 | time | | | 1. William Carr | United States | 48.8s | Q | | 2. George Golding | Australia | 49.0s | Q | | 3. Crew Stoneley | Great Britain | 49.1s | Q | | 4. Walter Nehb | Germany | 49.4s | | | 5. Khristos Mantikas |  Greece | 49.6s | | | 6. Manuel Álvarez | Mexico | 49.9s | |
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| Heat 5 | time | | | 1. Felix Rinner | Austria | 49.2s | Q | | 2. Godfrey Rampling | Great Britain | 49.5s | Q | | 3. Willie Walters | South Africa | 49.8s | Q | | 4. Stuart Alexander Black |  New Zealand | 49.9s | | | 5. Seiken Cho | Japan | 50.0s | |
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| Heat 6 | time | | | 1. James Gordon | United States | 50.6s | Q | | 2. Raymond Lewis | Canada | 50.7s | Q | | 3. Domingos Puglisi | Brazil | 50.8s | Q | | 4. Richard Arguello | Mexico | 50.9s | |
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