Robert Rowan III, 32, an assistant professor of chemistry at the University of Maryland, died of cancer Thursday at Sibley Memorial Hospital.

Dr. Rowan was an authority in the field of nuclear magnetic resonance spectroscopy, a method for studying the structure of molecules in solution.

He also had been engaged in a research project involving Myelin basic proteins (MBP), which are structural proteins involved in the coating of nerves.

Dr. Rowan was born in Caracas, Venezuela, and grew up in Westfield, N.J. He earned a bachelor's degree at Pomona College in Claremont, Calif. and master's and doctoral degrees at Harvard University.

Before joining the faculty at the University of Maryland, three years ago, he had held a postdoctoral fellow-ship at Carnegie-Mellon University in Pittsburg.

Survivors include his wife, Dr. Nancy Rowan, an assistant professor of chemistry at American University, a daughter, Marian, and a son, Robert William, all of the home in New Carrollton; his parents, Dr. and Mrs. Robert Rowan Jr., who both teach chemistry at New Mexico State University, of Las Cruces, N.M.; a sister, Mary Sue Rowan, of Ecuador, and a brother William of Berkeley, Calif.

The family suggests that expressions of sympathy be in the form of contributions to the Pomona College Fund.