Thornton W. Owen, 79, a retired president and board chairman of the Perpetual American Federal Savings and Loan Association who had been a leader in business, civic, and charitable endeavors in this area for many years, died July 4 in his summer home in Rehoboth Beach, Del., after a heart attack. He lived in Chevy Chase.

Mr. Owen was board chairman, of what was then the Perpetual Building Association of Washington, for 10 years before serving as its president from 1966 to 1976. He served again as board chairman before becoming director emeritus in 1979.

Perpetual is the largest savings and loan institution in this area and one of the largest in the nation. Over the years, it gained a reputation of lending to home buyers in Southeast Washington, and elsewhere, who found it impossible to secure loans elsewhere. Perpetual's reputation of lending throughout the city, without racial discrimination, was firmly established in studies.

The late Edward C. Baltz, who also had served as a Perpetual board chairman and president, once told The Post that officers and directors of his savings and loan were chosen for their great imagination as well as their civic and community spirit.

Mr. Owen was president of the Washington Board of Trade from 1950 to 1951, and served two terms during the 1950s on the old Citizens Advisory Council to the Commissioners of the District of Columbia. He was a past director of the city's Better Business Bureau and was general chairman of the 1951 Combined Community Chest-USO campaign. He had been a director and trustee of the Federal City Council.

Over the years, he also had been a trustee of the Washington City Orphan Asylum and the Landon School for Boys, and a director of the Metropolitan Police Boys Club, the D.C. Society for Crippled Children and the Washington YMCA. He was named the Washington Board of Trade's 1971 Man of the Year, and had received a 1967 Distinguished Service Award from the Cosmopolitan Club.

Mr. Owen was president of the Metropolitan Washington Savings and Loan League in the early 1970s, and was a past president of the Washington chapters of the Society of Residential Appraisers and American Institute of Real Estate Appraisers.

He was board chairman of the Greater Washington Industrial Investors Inc., a venture capital firm, and had sat on the boards of the American Security & Trust Co., Acacia Mutual Life Insurance Co., the National Mortgage and Investment Corp., and Peoples Drug Stores.

Mr. Owen was a native of Washington and graduated from the old McKinley Tech High School in 1922. Four years later, he earned a bachelor's degree in civil engineering and business administration at the Massachusetts Institute of Technology. About 1930, he joined Thomas J. Owen & Son Inc., real estate auctioneers and appraisers. He was its president for 23 years before becoming president of Perpetual.

Survivors include his wife, Collette, two sons, Thomas J., and Thornton W. Jr., all of Chevy Chase; and four grandchildren.