Swimming at the 2009 Southeast Asian Games – Men's 100 metre butterfly
# Swimming at the 2009 Southeast Asian Games – Men's 100 metre butterfly

The Men's 100 Butterfly swimming event at the 2009 SEA Games was held on December 11, 2009.

## Results

### Final

| Place | Swimmer | Nation | Time | Notes |
| - | - | - | - | - |
| 1 | Daniel Bego | Malaysia | 53.82 | GR |
| 2 | Donny Utomo | Indonesia | 55.53 | |
| 3 | Quy Phuoc Hoang | Vietnam | 55.65 | |
| 4 | Thai Nguyen Vo | Vietnam | 55.77 | |
| 5 | James Walsh | Philippines | 56.16 | |
| 6 | Chatmongkon N | Thailand | 56.21 | |
| 7 | Kevin Lim | Malaysia | 56.87 | |
| 8 | Jessie Lacuna | Philippines | 59.43 | |

### Preliminary heats

| Rank | Heat | Swimmer | Nation | Time | Notes |
| - | - | - | - | - | - |
| 1 | H2 | Chatmongkon N | Thailand | 55.87 | Q |
| 2 | H2 | James Walsh | Philippines | 56.63 | Q |
| 3 | H1 | Donny Utomo | Indonesia | 56.74 | Q |
| 4 | H1 | Thai Nguyen Vo | Vietnam | 56.76 | Q |
| 5 | H2 | Daniel Bego | Malaysia | 57.04 | Q |
| 6 | H2 | Quy Phuoc Hoang | Vietnam | 57.66 | Q |
| 7 | H1 | Kevin Lim | Malaysia | 58.52 | Q |
| 8 | H2 | Jessie Lacuna | Philippines | 58.87 | Q |
| 9 | H1 | Zaw Phyo Aung | Myanmar | 1:03.26 | |
| 10 | H1 | Glenn Victor | Indonesia | 1:09.41 | |
| 11 | H2 | Kun Narak | Cambodia | 1:12.88 | |
| 12 | H1 | T Thepphitack | Laos | 1:23.08 | |
