| POS | BIB | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|---|
| 1 | 496 | Ibrahim Al-Hamaidi |  KSA | 49.55 Q PB | 0.174 | 
| 2 | 278 | Richard Davenport |  GBR | 50.20 Q NJR | 0.153 | 
| 3 | 93 | Diego Venâncio |  BRA | 50.85 Q | 0.186 | 
| 4 | 168 | Yasser Lismet |  CUB | 50.96 Q | 0.177 | 
| 5 | 919 | VÃctor Solarte |  VEN | 51.69 | 0.168 | 
| 6 | 65 | Michaël Bultheel |  BEL | 52.21 | 0.161 | 
| 7 | 428 | Markino Buckley |  JAM | 52.89 | 0.204 | 
| 407 | Nicola Cascella |  ITA | DQ | 0.159 | 
| POS | BIB | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|---|
| 1 | 868 | Kerron Clement |  USA | 49.01 Q | 0.147 | 
| 2 | 884 | Brandon Johnson |  USA | 49.78 Q | 0.153 | 
| 3 | 696 | L.J. van Zyl |  RSA | 50.11 Q | 0.163 | 
| 4 | 686 | Wouter le Roux |  RSA | 50.32 Q | 0.183 | 
| 5 | 742 | El Hadji Sethe Mbow |  SEN | 50.68 NJR | 0.183 | 
| 6 | 236 | Teemu Linkosaari |  FIN | 51.87 | 0.187 | 
| 7 | 508 | Bandar Yahya Shraheli |  KSA | 51.92 | 0.203 | 
| 8 | 453 | Go Tanabe |  JPN | 52.20 | 0.156 |