To provide processes for efficiently and economically producing 2-chloro-1,1,1,2-tetrafluoropropane (R244bb) and 2,3,3,3-tetrafluoropropene (R1234yf) in an industrially practical manner.A process for producing 2-chloro-1,1,1,2-tetrafluoropropane, which comprises a chlorination step of reacting 1,2-dichloro-2-fluoropropane and chlorine in the presence of a solvent under irradiation with light to obtain 1,1,1,2-tetrachloro-2-fluoropropane, and a fluorination step of reacting the 1,1,1,2-tetrachloro-2-fluoropropane obtained in the chlorination step and hydrogen fluoride in the presence of a catalyst to obtain 2-chloro-1,1,1,2-tetrafluoropropane, and a process for producing 2,3,3,3-tetrafluoropropene, which comprises dehydrochlorinating it in the presence of a catalyst.