| 1789 | Uranium was discovered by Martin Heinrich Klaproth. |
| 1828 | Thorium discovered by Jons Jakob Berzlius. |
| 1895.11. 8 | Wilhelm Conrad Roentgen discovered X-ray discovered by. |
| 1896. 3. 1 | Radioactivity discovered by Henri Becquerel |
| 1898 | Alpha-ray and beta-ray discovered by Ernest Rutherford (Lord Nelson). They were distinguished by different transmissibility. |
| 1898.12.26 | Marie and Pierre Curie found Radium and polonium. |
| 1900 | Gamma-ray discovered by P.Villard. |
| 1903 | Theory of atomic decay and radioactivity presented by Ernest Rutherford and Frederic Soddy. |
| 1905 | Albert Einstein proposed Special theory of relativity . |
| 1908 | Hans Geiger develops Geiger Counter. |
| 1908 | Ernest Rutherford proved that Alpha-ray is same as helium nucleus. |
| 1913 | Frederick Soddy proposed isotopes. |
| 1915.11.25 | Albert Einstein gives General theory of relativity. |
| 1920 | E.Rutherford proposes concept of Proton. |
1930's - 1945
| 1930 | Discovery of radiation penetrating a leadblock by Walter Bethe. |
| 1932 | James Chadwick showed neutrons. |
| 1932 | Deuterium was discovered. |
| 1933 |
L.Szilard proposed the idea of chain reaction using a neutron. |
| 1934 | Radioactivity caused by slow neutrons found by Enrico Fermi. |
| 1936 | Liquid-drop model of atomic nucleus that explains fission was proposed by Sir Niels Bohr. |
| 1938 | Alfred Nier compared U-235 and U-238 |
| 1938 | Uranium nuclear fission successful. Barium found. |
| 1939 | Otto Frisch named Nuclear Fission. |
| 1939 | Nuclear fission of 235 uranium is caused by slow neutron, proposed by N.Bohr and John Archibald Wheeler. |
| 1939 | Idea of reactor by E.Fermi. |
| 1940 | 93rd element discovered. |
| 1940 | [England] A plan for a factory for separation of uranium 235 by F.Simon. |
| 1941 | Element no.94 is chemically separated. |
| 1941 | Attack on Pearl Harbor by Japan |
| 1942 | President Franklin Roosevelt authorized the atomic bomb development plan. |
| 1942 | Colonel James C. Marshall. creates Manhattan Engineering District (MED). |
| 1942 | Anglo-French atomic power accord. |
| 1942 | First Self-sustaining chain reaction carried out by Enrico Fermi. |
| 1944 | Mock use of thin man bomb failed. |
| 1945 | Otto Frisch Verifies of critical mass of uranium 235. |
| 1945 | Trinity test time-table decided. |
| 1945 | Harry Truman becomes US president due to death of Franklin roosevelt. |
| 1945 | Assembly of bomb for Trinity test. |
| 1945 | [U. S. A.] Preparatory implosion experiment declared indecisive by H. Bethe. |
| 1945 | TRINITY test performed. |
| 1945 | Little Boy shipped. |
| 1945.8.6 | Hiroshima, Japan bombed by the U.S. The bomb was 'little boy'. |
| 1945.8.9 | The U.S bombed Nagasaki with 'Fat Man'. 70,000 killed. |
| 1945.8 | Unconditional Surrender by Japan ending World War II |
| 1945 | U.S.Army destroys 5 Japanese cyclotron. |
| 1950 | Outbreak of Korean war. |
| 1952.8.6 | Japan builds Hiroshima, Nagasaki victims Memorial tower. |
| 1952.11.1 | The first H-bomb explosion by USA. |
| 1955 | First World Conference Against A-H Bomb held in Hiroshima in Japan. |
| 1958 | US decides to suspend nuclear tests. |
| 1960 | A-bomb test in Sahara desert. |
| 1961 | The US decides to resume nuclear tests. |
| 1962 | Cuban Missile Crisis. |
| 1963 | Limited Test Ban Treaty. |
| 1963 | Enrico Fermi award to J.R.Oppenheimer. |
| 1968 | Nuclear Non-Proliferation Treaty. |
| 1989 | Fall of East Berlin Wall. |
| 1989 | US Stops deploying nuclear depth bombs and ship-to-air warheads. |
| 1995 | Southeast Asia Nuclear Weapon-free Zone (SEANWFZ) Treaty signed by ASEAN Countries. |
| 1996 | Russia holds Atomic energy. |
| 1996 | Nuclear test by china. |
| 1996 | Comprehensive Test Ban Treaty (CTBT) was signed by US, Russia but failed due to India's refusal. |
| 1997 | Southeast Asia Nuclear Weapon-free Zone Treaty (Bankok Treaty) signed. |
| 1998. 5.11 | India conducts Pokhran nuclear tests. |
| 1998. 5.13 | India conducts another test. |
| 1998. 5.28 | Pakistan conducts Baluchistan test insisting India's threat. |
| 1998. 5.30 | Another Test by Pakistan. |