A vapor phase process is disclosed for making internal fluorobutenes. The process involves contacting a halobutane starting material selected from the group consisting of CF2HCHClCH2CCl2H, CF2HCHClCH2CCl3, CF3CHClCH2CCl2H, CF3CHClCH2CCl3, CF3CHClCHClCCl2H, CF3CHClCHClCCl3, CF3CCl2CH2CCl2H, CF3CCl2CH2CCl3, CF3CCl2CHClCCl2H, CF3CCl2CHClCCl3, CF3CClFCHClCCl2H, CF3CClFCHClCCl3, CF3CClFCH2CCl2H, CF3CClFCH2CCl3, CF3CClFCHFCCl2H, CF3CClFCHFCCl3, CF3CClHCHFCCl2H and CF3CClHCHFCCl3, with HF in a reaction zone in the presence of a chromium oxyfluoride catalyst to produce a product mixture comprising an internal fluorobutene. Another vapor phase process is disclosed for making internal fluoropentenes. The process involves contacting a halopentane starting material selected from the group consisting of CF2HCHXCH2CX2CX3, CF3CHXCH2CX2CX3, CF3CHXCHXCX2CX3, CF3CX2CH2CX2CX3, CF3CX2CHXCX2CX3 and CF3CHXCHFCX2CX3, with HF in a reaction zone in the presence of a chromium oxyfluoride catalyst to produce a product mixture comprising an internal fluoropentene, wherein each X is independently selected from the group consisting of F, Cl and Br, provided that not all X are fluorines.