Chemical weapons, like all military technology, are associated with activities of scientists and engineers. However, chemical weapons differ from any other military technology because they were invented, and their first mass use directly developed by famous chemists. The active contribution of engineers and scientists and their organisations in the negotiations on chemical disarmament, including drafting the Chemical Weapons Convention, is described. Their present and future role in implementing the Convention is analysed, taking into consideration the threats and benefits of advances in science and technology, and stressing the independent expertise of the OPCW Scientific Advisory Board.