Lucile Donovan Brennecke, 85, who worked for the federal government here for more than 30 years and who also was an employe of the United Nations and an attorney, died May 20 at the Florence Nightingale nursing home in New York City. She had cancer.

Mrs. Brennecke was born in Terre Haute, Ind., and graduated from what is now Indiana State University. She was a school teacher in the Terre Haute area before moving to Washington in 1916.

She worked for the Old War Department for several years and earned a law degree from George Washington University in 1929. During the 1930s, she became a librarian at the Securities and Exchange Commission. In 1948 and 1949, she was a reference librarian at the Central Intelligence Agency.

Mrs. Brennecke also worked for the United Nations Relief and Rehabilitation Administration in Washington and engaged in a private law practice. At one time she was employed by the Woodward & Lothrop department store.

In 1966, she married Dr. Ernest Brennecke, a professor emeritus of English at Columbia University and she lived in New York City after that. Dr. Brennecke died in 1969.

Mrs. Brennecke's survivors include two brothers, Dr. Paul B. Donovan, of San Diego, Calif., and John Timothy Donovan, of Chevy Chase.