Disclosed is a process for the synthesis of 1,3,3,3-tetrafluoropropene which comprises, in one embodiment, reacting a compound of CF3X1 with a compound of CX2H═CHX3, wherein X1, X2, and X3 are each independently selected from the group consisting of fluorine, chlorine, bromine and iodine, to produce a reaction product comprising a compound of CF3CH═CHX3, wherein X3 is as described above; and when X3 is not fluorine, fluorinating the compound to produce 1,3,3,3-tetrafluoropropene. The process in another embodiment comprises preparing tetrafluoropropene comprising thermally cracking one or more compounds capable of producing a reaction mixture which preferably comprises diflurocarbene radicals and vinylidene fluoride, and converting said reaction mixture into—tetrafluoropropene (1,3,3,3-tetrafluoropropene).