To obtain 3-trifluoromethyl-1,1,1,2,2-pentafluorobutane which is useful as a detergent which can take a place of specific flons by allowing trifluoromethyl-pentafluorobutene to react with hydrogen in the presence of a hydrogenation catalyst.

In the presence of a hydrogenation catalyst (preferably platinum or palladium, preferably carried by a catalyst carrier such as a metal oxide, for example, silica, alumina or activated carbon, (B) hydrogen is allowed to react with (C) 3-trifluoro-methyl-1,1,1,2,2-pentafluoro-4-butene to give (D) 3- trifluoro-methyl-1,1,1,2,2-pentafluorobutane. In a preferred embodiment, the reaction is carried out in a vapor phase, the amount of component B is 1-20 moles, preferably 2-5 moles per mole of the component C, the reaction temperature is 0°C-30°C, preferably 50°C-200°C and the reaction pressure is the normal pressure to 1MPa, preferably the normal pressure to 0.2MPa.