The field-ion mass spectra of eleven alkynes are reported and the type of field dissociation observed is discussed. The alkynes obey well the rules developed 5 for field dissociation, in some ways their behaviour resembling that of the alkenes and in others that of the alcohols. New effects have been observed such as the occurrence of metastable transitions from products of ion-molecule reactions, and the formation of ions from associated water + hydrocarbon species.