A process for the preparation of cis-1,1,1,4,4,4-hexafluoro-2-butene comprising: a) contacting 1,1,1-trifluorotrichloroethane with hydrogen in the presence of a catalyst comprising ruthenium to produce a product mixture comprising 1316mxx; b) recovering said 1316mxx as a mixture of Z- and E- isomers; c) contacting said 1316mxx with hydrogen, in the presence of a catalyst selected from the group consisting of copper on carbon, nickel on carbon, copper and nickel on carbon and copper and palladium on carbon, to produce a second product mixture, comprising E- or Z-CFC-1326mxz; d) subjecting said second product mixture to a separation step to provide E- or Z-1326mxz; and further contacting said E- or Z-1326mxz with an aqueous solution of an alkali metal hydroxide in the presence of a quaternary alkylammonium salt having alkyl groups of from four to twelve carbon atoms and mixtures thereof, wherein at least said Z-1326mxz is converted to produce a mixture comprising hexafluoro-2-butyne, and recovering the hexafluoro-2-butyne; or further contacting said E- or Z-1326mxz with an aqueous solution of an alkali metal hydroxide in the presence of a quaternary alkylammonium salt which comprises at least one alkyl group of at least 8 carbons, wherein at least said E-1326mxz is converted to produce a mixture comprising hexafluoro-2-butyne, and recovering the hexafluoro-2-butyne; the process further comprising contacting said hexafluoro-2-butyne with hydrogen in the presence of a catalyst of palladium on a support, and at least one element selected from the group consisting of lanthanum, cerium and silver, to produce Z-1,1,1,4,4,4-hexafluoro-2-butene. a) contacting 1,1,1-trifluorotrichloroethane with hydrogen in the presence of a catalyst comprising ruthenium to produce a product mixture comprising 1316mxx; b) recovering said 1316mxx as a mixture of Z- and E- isomers; c) contacting said 1316mxx with hydrogen, in the presence of a catalyst selected from the group consisting of copper on carbon, nickel on carbon, copper and nickel on carbon and copper and palladium on carbon, to produce a second product mixture, comprising E- or Z-CFC-1326mxz; d) subjecting said second product mixture to a separation step to provide E- or Z-1326mxz; and further contacting said E- or Z-1326mxz with an aqueous solution of an alkali metal hydroxide in the presence of a quaternary alkylammonium salt having alkyl groups of from four to twelve carbon atoms and mixtures thereof, wherein at least said Z-1326mxz is converted to produce a mixture comprising hexafluoro-2-butyne, and recovering the hexafluoro-2-butyne; or further contacting said E- or Z-1326mxz with an aqueous solution of an alkali metal hydroxide in the presence of a quaternary alkylammonium salt which comprises at least one alkyl group of at least 8 carbons, wherein at least said E-1326mxz is converted to produce a mixture comprising hexafluoro-2-butyne, and recovering the hexafluoro-2-butyne; the process further comprising contacting said hexafluoro-2-butyne with hydrogen in the presence of a catalyst of palladium on a support, and at least one element selected from the group consisting of lanthanum, cerium and silver, to produce Z-1,1,1,4,4,4-hexafluoro-2-butene. further contacting said E- or Z-1326mxz with an aqueous solution of an alkali metal hydroxide in the presence of a quaternary alkylammonium salt having alkyl groups of from four to twelve carbon atoms and mixtures thereof, wherein at least said Z-1326mxz is converted to produce a mixture comprising hexafluoro-2-butyne, and recovering the hexafluoro-2-butyne; or further contacting said E- or Z-1326mxz with an aqueous solution of an alkali metal hydroxide in the presence of a quaternary alkylammonium salt which comprises at least one alkyl group of at least 8 carbons, wherein at least said E-1326mxz is converted to produce a mixture comprising hexafluoro-2-butyne, and recovering the hexafluoro-2-butyne; the process further comprising contacting said hexafluoro-2-butyne with hydrogen in the presence of a catalyst of palladium on a support, and at least one element selected from the group consisting of lanthanum, cerium and silver, to produce Z-1,1,1,4,4,4-hexafluoro-2-butene.