NEW MATERIAL:A fluorine-containing 2-amino (or alkylamino)-2-thiazoline compound expressed by formulaI(Rf, Rf' and Rf" are fluoroalkyl; R is H or alkyl).

EXAMPLE: 2-Amino-4,4-bis(trifluoromethyl)-5-(tetrafluoroethylidene)-2-thiazoline.

USE: A medicine, chemically stable, and capable of exhibiting improved physiological activity.

PROCESS: A fluorine-containing aliphatic compound expressed by formula II is reacted with thiourea or a derivative thereof expressed by formula III in an aprotic solvent, e.g. dimethylformamide (DMF), to give a fluorine-containing thiazolidine compound expressed by formula IV, which is then isomerized with a mineral acid, e.g. sulfuric acid, to afford the compound expressed by formulaI.