Disclosed is a process for the co-manufacture of the hydrofluoroolefins HFC-1225ye and HFC-1234yf. The process comprises contacting a blend of 1,1,1,2,3,3-hexafluoropropane and 1,1,1,2,3-pentafluoropropane at a temperature of from about 200.degree. C. to about 500.degree. C. with a catalyst, optionally in the presence of an inert gas. The catalyst includes, but is not limited to, aluminum fluoride; fluorided alumina; metals on aluminum fluoride; metals on fluorided alumina; oxides, fluorides, and oxyfluorides of magnesium, zinc and mixtures of magnesium and zinc and/or aluminum; lanthanum oxide and fluorided lanthanum oxide; chromium oxides, fluorided chromium oxides, and cubic chromium trifluoride; carbon, acid-washed carbon, activated carbon, three dimensional matrix carbonaceous materials; and metal compounds supported on carbon. The metal compounds are oxides, fluorides, and oxyfluorides of at least one metal selected from the group consisting of sodium, potassium, rubidium, cesium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, chromium, iron, cobalt, rhodium, nickel, copper, zinc, and mixtures thereof. The product hydrofluoroolefins are separated from unreacted hydrofluorocarbons and hydrogen fluoride. In another embodiment, the unreacted hydrofluorocarbons optionally may be recirculated back through the process.