Schedule 1 substances, in the sense of the Chemical Weapons Convention, are chemicals which are feasible either to be used directly as chemical weapons or in the manufacture of chemical weapons, and which have very limited to no use outside of chemical warfare. These may be produced or used for research, medical, pharmaceutical or chemical weapon defence testing (called "protective testing" in the treaty) purposes but production above 100 grams per year must be declared to the OPCW in accordance with Part VI of the "Verification Annex". A country is limited to possessing a maximum of one tonne of these materials. Schedule 1 is divided into Part A substances, which are chemicals that can be used directly as weapons, and Part B which are precursors useful in the manufacture of chemical weapons. Examples are mustard and nerve agents, and substances which are solely used as precursor chemicals in their manufacture. A few of these chemicals have very small-scale non-military applications; for example, minute quantities of nitrogen mustard are used to treat certain cancers. The Schedule 1 list is one of three lists. Chemicals which are feasible to use as weapons, and their precursors, but which have legitimate applications as well are listed in Schedule 2 (small-scale applications) and Schedule 3 (large-scale applications). The use of Schedule 1, 2, or 3 chemicals as weapons is banned by the Convention.

Guidelines for Schedule 1

The following criteria shall be taken into account in considering whether a toxic chemical or precursor should be included in Schedule 1:

Toxic chemicals

Precursors