ExxonMobil Corp.’s (NYSE: XOM) board of directors appointed Neil Duffin to replace Tom Walters as president of ExxonMobil Production Co. Duffin was also elected as a vice president of the corporation.

Duffin is currently the president of ExxonMobil Development Co.—since 2007-- and Walters is retiring after more than 38 years of service, according to a Dec. 2 press release.

Duffin joined Mobil in 1979 in Aberdeen, Scotland, and has held managerial positions in production, operations and development.

In 1992, he was named producing advisor for Europe and Africa based in Fairfax, Va. In 1995, he moved to Aberdeen, Scotland, as operations and northern North Sea manager. In 1998, he was named senior vice president of Mobil Oil Indonesia.

Duffin became vice president of ExxonMobil Development Co. for Russia/Caspian Sea and the Middle East in 1999. He became vice president of ExxonMobil Production Co. for Africa in 2004. He became executive vice president of ExxonMobil Development Co. in 2006.

Duffin earned a bachelor’s degree from Heriot Watt University in the U.K.

Walters was appointed to his current role in 2013. He first joined Exxon USA in 1978 in Los Angeles and has held technical and managerial positions in production, operations, development and global services.

In 1999, he was appointed as vice president for Africa for ExxonMobil Development Co. and in 2002, was appointed as vice president for the U.S. for ExxonMobil Production Co.

Walters was appointed as president of ExxonMobil Global Services Co. in 2005, prior to becoming executive vice president of ExxonMobil Development Co. in 2007. He became president of ExxonMobil Gas & Power Marketing Co. in 2009.

Walters earned a bachelor’s degree from Vanderbilt University and a master’s degree from Texas A&M University.

The Dec. 2 press release also said that Liam Mallon, who is currently executive vice president of ExxonMobil Development Co., has been elected president of ExxonMobil Development Co. by the board. He was appointed to his current position in 2014.

Mallon joined Mobil in 1990 in Aberdeen, Scotland, and held progressively senior positions before he became operations manager in Nigeria in 1998. He moved to Australia in the same capacity in 2000, and in 2003 relocated to Houston, where he was planning manager for ExxonMobil Production Co.

In 2004, Mallon was appointed president of ExxonMobil Canada, and in 2006 he was appointed director and chairman of ExxonMobil subsidiaries in Malaysia. He became vice president of engineering for ExxonMobil Production Co. in 2009 and vice president for Africa in 2012.

Mallon earned a bachelor’s degree from Trinity College in Dublin, Ireland, and a master’s degree from Heriot Watt University.

All management changes are effective Jan. 1, 2017.