Kathleen C. McNamara, 53, who was active in Catholic lay organizations, died Thursday at Georgetown University Hospital of complications following surgery.

Mrs. McNamara had served in the Christ Child Society, first as president of the Kensington chapter and then as a national vice president during the 1970s.

She had been executive vice president of the John Carroll Society for eight years.

She also had worked for several years as a volunteer librarian at the Holy Redeemer Grade School and in scouting organizations at the Holy Redeemer Catholic Church in Kensington, of which she was a member.

Mrs. McNamara was born in Wisconsin and moved to Washington in 1934. She was a graduate of the Sacred Heart Academy and Dunbarton College.

She worked for about three years for the State Department during the 1940s and then for about two years for the National Catholic Welfare Conference.

She is survived by her husband, Martin J. McNamara Jr., four sons, Thomas, Daniel, Robert, and Michael, and a daughter, Kathleen, all of the home in Kensington; two other sons, Martin J. III and John, both of Wheaton; three other daughters, Patricia Anne, of Washington; Mary E. Rice, of Great Falls, Va., and Mary B. Novel, of Kensington, and four sisters, Anne Mann, of Washington; Helen Owens, of Bethesda; Mary Moran, of Cumberland, Md., and Jeanne Mathews, of Ashland, Ky.

The family suggests that expressions of sympathy be in the form of contributions to the Christ Child Society.