# Swimming at the 2011 World Aquatics Championships – Men's 100 metre butterfly

The men's 100 metre butterfly competition of the swimming events at the 2011 World Aquatics Championships was held on July 29 with the heats and the semifinals and July 30 with the final.

## Records

Prior to the competition, the existing world and championship records were as follows.
| | Name | Nation | Time | Location | Date |
| World record Championship record | Michael Phelps | United States | 49.82 | Rome | August 1, 2009 |

## Results
### Heats

66 swimmers participated in 9 heats.
| Rank | Heat | Lane | Name | Nationality | Time | Notes |
| 1 | 8 | 5 | Tyler McGill | United States | 51.76 | Q |
| 2 | 7 | 3 | Takuro Fujii | Japan | 51.82 | Q |
| 3 | 9 | 5 | Geoff Huegill | Australia | 51.83 | Q |
| 4 | 8 | 7 | Jason Dunford | Kenya | 51.87 | Q |
| 5 | 8 | 4 | Michael Phelps | United States | 51.95 | Q |
| 6 | 7 | 6 | Konrad Czerniak | Poland | 52.10 | Q |
| 7 | 7 | 5 | Yevgeny Korotyshkin | Russia | 52.18 | Q |
| 8 | 7 | 4 | Benjamin Starke | Germany | 52.26 | Q |
| 9 | 9 | 3 | Joeri Verlinden | Netherlands | 52.27 | Q |
| 10 | 9 | 8 | Sam Ashby | Australia | 52.27 | Q |
| 11 | 9 | 6 | László Cseh | Hungary | 52.40 | Q |
| 12 | 9 | 1 | Peter Mankoč | Slovenia | 52.46 | Q |
| 13 | 6 | 6 | Chad le Clos | South Africa | 52.54 | Q |
| 14 | 8 | 6 | Steffen Deibler | Germany | 52.54 | Q |
| 15 | 9 | 7 | Lars Frölander | Sweden | 52.56 | Q |
| 16 | 8 | 1 | Paweł Korzeniowski | Poland | 52.57 | Q |
| 17 | 6 | 3 | François Heersbrandt | Belgium | 52.65 | |
| 18 | 9 | 2 | Milorad Čavić | Serbia | 52.67 | |
| 19 | 7 | 2 | Antony James | Great Britain | 52.68 | |
| 20 | 8 | 8 | Ryan Pini | Papua New Guinea | 52.69 | |
| 21 | 6 | 2 | Joseph Bartoch | Canada | 52.90 | |
| 22 | 6 | 7 | Simão Morgado | Portugal | 53.01 | |
| 23 | 6 | 8 | Pavel Sankovich | Belarus | 53.13 | |
| 24 | 7 | 7 | Ivan Lenđer | Serbia | 53.14 | |
| 25 | 7 | 1 | Michael Rock | Great Britain | 53.20 | |
| 26 | 8 | 2 | Kaio Almeida | Brazil | 53.20 | |
| 27 | 5 | 1 | Ben Hockin | Paraguay | 53.23 | |
| 28 | 8 | 3 | Zhou Jiawei | China | 53.23 | |
| 29 | 5 | 3 | Lorenzo Benatti | Italy | 53.38 | |
| 30 | 7 | 8 | Nikita Konovalov | Russia | 53.49 | |
| 31 | 5 | 2 | Vytautas Janušaitis | Lithuania | 53.50 | |
| 32 | 5 | 6 | Dominik Meichtry | Switzerland | 53.54 | NR |
| 33 | 6 | 1 | Mario Todorović | Croatia | 53.56 | |
| 34 | 6 | 5 | Octavio Alesi | Venezuela | 53.56 | |
| 35 | 6 | 4 | Wu Peng | China | 53.59 | |
| 36 | 4 | 3 | Ham Jong-Hun | South Korea | 53.94 | |
| 37 | 5 | 7 | Jan Šefl | Czech Republic | 53.97 | |
| 38 | 5 | 8 | Shaune Fraser | Cayman Islands | 54.19 | |
| 39 | 5 | 5 | Hoàng Quý Phước | Vietnam | 54.39 | |
| 40 | 4 | 4 | Bradley Ally | Barbados | 54.42 | |
| 41 | 4 | 5 | Hsu Chi-Chieh | Chinese Taipei | 54.44 | |
| 42 | 4 | 2 | Yeugeniy Lazuka | Azerbaijan | 54.70 | |
| 43 | 4 | 6 | Alex Hernandez Medina | Cuba | 55.34 | |
| 44 | 5 | 4 | Stefanos Dimitriadis | Greece | 55.41 | |
| 45 | 4 | 1 | Joshua McLeod | Trinidad and Tobago | 55.80 | |
| 46 | 4 | 7 | Rami Anis | Syria | 56.47 | |
| 47 | 2 | 4 | Brad Hamilton | Jamaica | 56.48 | NR |
| 48 | 3 | 5 | Marcelino Richaards | Suriname | 56.51 | |
| 49 | 2 | 5 | Ifalemi Paea | Tonga | 56.60 | |
| 50 | 4 | 8 | Saeed Ashtiani | Iran | 56.83 | |
| 51 | 3 | 1 | Rommie Benjamin | Dominican Republic | 57.11 | |
| 52 | 3 | 4 | Édgar Crespo | Panama | 57.24 | |
| 53 | 3 | 2 | Javier Hernandez | Honduras | 57.40 | |
| 54 | 3 | 3 | Donny Utomo | Indonesia | 57.59 | |
| 55 | 3 | 7 | Oluseyi Fatayi-Williams | Nigeria | 57.96 | |
| 56 | 3 | 6 | Joao Matias | Angola | 58.20 | |
| 57 | 3 | 8 | Sofyan El Gadi | Libya | 58.38 | |
| 58 | 2 | 3 | Andrey Molchanov | Turkmenistan | 1:00.83 | |
| 59 | 2 | 1 | Iohanad Dheyaa | Iraq | 1:01.10 | |
| 60 | 2 | 6 | Alban Laye-Joseph Diop | Senegal | 1:01.60 | |
| 61 | 2 | 7 | Amer Ali | Iraq | 1:01.88 | |
| 62 | 2 | 2 | Adama Ouedraogo | Burkina Faso | 1:03.29 | NR |
| 63 | 2 | 8 | Khalid Ismaeel Alibaba | Bahrain | 1:05.40 | |
| 64 | 1 | 3 | Beni-Bertrand Binobagira | Burundi | 1:19.76 | |
| 65 | 1 | 4 | Janvier Niyonkuru | Burundi | 1:27.01 | |
| | 1 | 5 | Fiseha Hailu | Ethiopia | | DSQ |

### Semifinals

The semifinals were held at 19:01.

#### Semifinal 1

| Rank | Lane | Name | Nationality | Time | Notes |
| 1 | 3 | Konrad Czerniak | Poland | 51.54 | Q, NR |
| 2 | 4 | Takuro Fujii | Japan | 51.69 | Q |
| 3 | 5 | Jason Dunford | Kenya | 51.92 | Q |
| 4 | 6 | Benjamin Starke | Germany | 52.18 | |
| 5 | 2 | Sam Ashby | Australia | 52.19 | |
| 6 | 8 | Paweł Korzeniowski | Poland | 52.54 | |
| 7 | 1 | Steffen Deibler | Germany | 52.55 | |
| 8 | 7 | Peter Mankoč | Slovenia | 52.67 | |

#### Semifinal 2

| Rank | Lane | Name | Nationality | Time | Notes |
| 1 | 3 | Michael Phelps | United States | 51.47 | Q |
| 2 | 4 | Tyler McGill | United States | 51.56 | Q |
| 3 | 6 | Yevgeny Korotyshkin | Russia | 51.77 | Q |
| 4 | 5 | Geoff Huegill | Australia | 51.85 | Q |
| 5 | 2 | Joeri Verlinden | Netherlands | 51.97 | Q |
| 6 | 7 | László Cseh | Hungary | 52.18 | |
| 7 | 8 | Lars Frölander | Sweden | 52.34 | |
| 8 | 1 | Chad le Clos | South Africa | 52.44 | |

### Final

The final was held at 18:42.
| Rank | Lane | Name | Nationality | Time | Notes |
| | 4 | Michael Phelps | United States | 50.71 | |
| | 5 | Konrad Czerniak | Poland | 51.15 | NR |
| | 3 | Tyler McGill | United States | 51.26 | |
| 4 | 1 | Jason Dunford | Kenya | 51.59 | |
| 5 | 6 | Takuro Fujii | Japan | 51.75 | |
| 6 | 2 | Yevgeny Korotyshkin | Russia | 51.86 | |
| 7 | 8 | Joeri Verlinden | Netherlands | 52.21 | |
| 8 | 7 | Geoff Huegill | Australia | 52.36 | |