A novel method, based on superpotentials is proposed for obtaining thequasi-normal modes of anti-de Sitter black holes. This is inspired by thecase of the three-dimensional BTZ black hole, where the quasi-normalmodes can be obtained exactly and are proportional to the surface gravity.Using this approach, the quasi-normal modes of the five-dimensionalSchwarzschild anti-de Sitter black hole are computed numerically. Themodes again seem to be proportional to the surface gravity for very smalland very large black holes. They reflect the well known instability ofsmall black holes in anti-de Sitter space.