Abstract: A fluorinated saturated hydrocarbon represented by the formula (2): ##STR1## wherein R and R' represent a perfluoroalkyl group or both R and R' are bonded together to form a perfluoroalkylene group which is a part of a ring, is industrially advantageously produced with good operating characteristics by reacting a fluorinated unsaturated hydrocarbon represented by the formula (1):R --CF.dbd.CF-R' (1)wherein R and R' are as defined above, with hydrogen in the presence of a platinum catalyst.

Abstract: A process for preparation of a gem-difluoroalkane is provided which comprises(A) a step to add a fluorinated alkane having a boiling point of -30.degree. to 30.degree. to a crude alkyne having 3 or 4 carbon atoms containing a polymerizable olefin as an impurity, and distill the mixture to remove the polymerizable olefin,(B) a step to react hydrogen fluoride with the fluorinated alkane and the alkyne having 3 or 4 carbon atoms obtained in the above step to synthesize the gem-difluoroalkane, and(C) a step to distill the reaction solution of the above (B) to obtain the gem-difluoroalkane.According to this process, gem-difluoroalkanes can be prepared more economically compared with usual processes.