Einar Olaf Olsen, 90, who worked for the Commerce Department for 23 years before retiring in 1987 as an official in its International Trade Administration, died of an aneurysm Nov. 28 at Reston Hospital. He lived in Great Falls.

Mr. Olsen served dually as a trade specialist and foreign service officer in the mid-1970s, when he was assigned to the U.S. consulate in Frankfurt, Germany, and as deputy director of the U.S. trade center there.

Mr. Olsen was born on Staten Island, N.Y., to Norwegian parents. He grew up in Norway, where he graduated from Oslo Commercial College and worked in that city as a shipping clerk for a pulp company.

During World War II, he spent two months in Nazi captivity before being released. He also helped track German collaborators. He then moved to London, where he ran a distribution network for the CARE foreign aid group from 1947 to 1952 and headed a logistical support office at United Nations headquarters from 1953 to 1964.

He began his Commerce Department career in 1964, promoting American products overseas as deputy director of the U.S. trade center in Stockholm.

Mr. Olsen was a member of DACOR (Diplomatic and Consular Officers, Retired) and Lewinsville Presbyterian Church in McLean.

Survivors include his wife, Bergljot, of Great Falls; three children, Einar Scott Olsen of Arlington, Monica Olsen of Seattle and Ann Moran of Claremont, Calif.; and two grandchildren.