| 1970 | ITOCHU established Japan Low Sulfur Oil Co., Ltd. (JALOSCO) to conduct hydrocarbon exploration and production activities of offshore Southeast Sumatra (SES) and offshore Northwest Java (ONWJ) in Indonesia |
| 1971 | The first production of Cinta crude oil and Ardjuna crude oil |
| 1972 | Establishment of C. Itoh Energy Development Co., Ltd. (CIECO) for the exploration of the Vogelkop region in Indonesia Crude oil discovery in Kasim, Vogelkop |
| 1973 | The first production of Walio (Kasim) crude oil |
| 1977 | The first shipment of Ardjuna LPG |
| 1984 | CIECO merged with JALOSCO |
| 1987 | Crude oil discovery in Intan, offshore Southeast Sumatra |
| 1988 | Crude oil discovery in Widuri, offshore Southeast Sumatra |
| 1990 | Production Sharing Contract with Pertamina for the Kepala Burung block |
| 1991.1. | Acquisition of an additional working interest in onshore Vogelkop block |
| 1992.9. | Acquisition of an additional working interest in offshore Southeast Sumatra block |
| 1993.1. | Commencement of production from Kepala Burung block |
| 1993.2. | Acquisition of an additional working interest in offshore Southeast Sumatra block |
| 1993.4. | C. Itoh Energy Development Co., Ltd. changed its name to ITOCHU Oil Exploration Co., Ltd. |
| 1993.5. | Acquisition of interests in three U.K. North Sea fields (Hutton, Northwest Hutton, and Hudson) |
| 1995.3. | Acquisition of shares of Sakhalin Oil and Gas Development Co., Ltd.(SODECO) |
| 1996.3. | Acquisition of a working interest in Azeri, Chirag, and Deepwater Gunashli, South Caspian, Azerbaijan |
| 1996.7. | Acquisition of an additional working interest in Azeri, Chirag, and Deepwater Gunashli, South Caspian, Azerbaijan |
| 1997.11. | The first production of Azeri light crude Oil |
| 1998.12. | Acquisition of a working interest in Atashkyakh, Yanan Tava, and Mugan Deniz, South Caspian, Azerbaijan Acquisition of a working interest in block 28/3, U.K. North Sea |
| 2000.7. | Acquisition of a working interest in Algeria Ohanet gas field |
| 2002.6. | Acquisition of interests in the Baku-Tbilisi-Ceyhan (BTC) Pipeline project |
| 2003.10. | The first production of Algeria Ohanet gas |
| 2004.3. | Succession by ITOCHU to the energy resource development business formerly belonging to CIECO |
| 2004.5. | Acquisition of a working interest in the Cliff Head oil field, Australia |
| 2005.6. | Acquisition of a working interest in the Alba field, the U.K. North Sea |
| 2006.5. | The first production from the Cliff Head oil field |
| 2006.6. | The first transportation of ACG crude via the BTC Pipeline |
| 2007.1. | Acquisition of exploration lease interests in the GoM Texas State Water |
| 2007.3. | Acquisition of lease interests in 15 producing fields in the GoM offshore |
| 2007.10. | Acquisition of production license interests in the offshore Victoria in the southeast area of Australia |
| 2008.5. | Acquisition of exploration blocks in Faroese Continental Shelf |
| 2008.7. | Acquisition of exploration blocks in west of Shetland |
