Disclosed is a process which achieves improved selectively of HFC-125 and/or improved HFC/HCFC ratio (and particularly HFC-125/CFC-115 ratio) by a fluorination process which comprises reacting PCE and HF in a first reaction train to produce a reaction product comprising at least (HCFC-124), separating from this reaction product at least a portion of the HCFC-124; and reacting the separated HCFC-124 with HF in a second reaction train to produce a second reaction product containing at least HFC-125.
