Imidazo[2,1-b]thiazoles carrying in the 2-position a phenyl radical unsubstituted or substituted by one or two atoms or radicals selected from halogen atoms and alkyl, alkoxy, alkylthio, dialkylamino, dialkylsulphamoyl, nitro, cyano and trifluoromethyl radicals or carrying in the 2-position a 2-, 3- or 4-pyridyl radical unsubstituted or substituted by an alkyl or alkoxy radical, are new compounds possessing pharmacological properties and useful, in particular, as anti-depressants and psycho-energisers.