| POS | BIB | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|---|
| 1 | 1385 | Kerron Clement |  USA | 48.35 Q | 0.156 | 
| 2 | 1216 | Karsten WARHOLM |  NOR | 48.43 Q | 0.175 | 
| 3 | 844 | Juander SANTOS |  DOM | 48.59 q PB | 0.192 | 
| 4 | 1092 | Kemar MOWATT |  JAM | 48.66 q | 0.204 | 
| 5 | 606 | Abdelmalik LAHOULOU |  ALG | 49.33 | 0.186 | 
| 6 | 1236 | Patryk DOBEK |  POL | 49.40 | 0.158 | 
| 7 | 922 | Victor COROLLER |  FRA | 55.69 | 0.170 | 
| 1053 | Thomas BARR |  IRL | DNS | 
| POS | BIB | ATHLETE | COUNTRY | MARK | ms* | Reaction Time | 
|---|---|---|---|---|---|---|
| 1 | 1405 | TJ HOLMES |  USA | 49.12 Q | 0.187 | |
| 2 | 1298 | Kariem HUSSEIN |  SUI | 49.13 Q | 0.147 | |
| 3 | 1087 | Jaheel HYDE |  JAM | 49.75 | 0.157 | |
| 4 | 959 | Jack Green |  GBR | 49.93 | .927 | 0.230 | 
| 5 | 1101 | Takatoshi ABE |  JPN | 49.93 | .929 | 0.212 | 
| 6 | 928 | Mamadou Kasse HANN |  FRA | 50.35 | 0.165 | |
| 7 | 1137 | Aron Kipchumba KOECH |  KEN | 50.40 | 0.174 | |
| 8 | 882 | Jaak-Heinrich Jagor |  EST | 50.43 | 0.149 | 
ms - Milliseconds - shown when two or more competitors finish with the same time down to hundredths of a second
| POS | BIB | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|---|
| 1 | 1268 | Abderrahman Almoubarrake S ALSALECK |  QAT | 48.75 Q | 0.247 | 
| 2 | 1345 | Yasmani COPELLO |  TUR | 48.91 Q | 0.203 | 
| 3 | 1394 | Eric Futch |  USA | 49.30 | 0.150 | 
| 4 | 942 | Ludvy VAILLANT |  FRA | 49.95 | 0.205 | 
| 5 | 1060 | José Reynaldo Bencosme De Leon |  ITA | 50.29 | 0.186 | 
| 6 | 1079 | Ricardo Cunningham |  JAM | 50.54 | 0.216 | 
| 628 | Guillermo Ruggeri |  ARG | DQ | 0.198 | |
| 731 | Marcio TELES |  BRA | DNF | 0.175 |