After nearly four years as CEO of Royal Dutch Shell (NYSE:RDS-A) (NYSE:RDS-B), Peter Voser will retire in the first half of next year, the company announced today.

Voser has been an executive director at Shell since 2004, and retained that title after being named CEO in July 2009. Shell Chairman Jorma Ollila was quoted in the company press release as saying, "Peter's leadership of Shell over the last 4 years has been impressive, reorganizing the company, delivering growth, and developing a clear forward strategy with a strong portfolio of new options. I have enjoyed working with Peter, in a period of great change and progress for Shell, and I wish him well for the future."

Voser first joined the Royal Dutch/Shell group of companies in 1982.

Shell intends to conduct a "structured and comprehensive review of internal and external candidates" in its search for Voser's successor, the company said.