O’Donnell wrote and presented over 100 television and radio documentaries. They included the ground-breaking BBC Television series "O’Donnell Investigates..." (1985–89) which presented the links emerging in the 1980s between diet, social behaviour, and disease, and two Tuesday documentaries for Yorkshire Television (YTV): "Part of Life" (1981), which explored the nature of teenage suicide, and "Is Your Brain Really Necessary?" (1982). He was scientific adviser on the Lindsay Anderson film "O Lucky Man!" (1973) and for a number of YTV popular science programmes, including "Don't Ask Me", "Don't Just Sit There", and "Where There's Life" (1979–83)