Abstract: What is described is a process for preparing a more effective catalyst for the vapor-phase reaction of 1,1,1,3-tetrachloropropane with anhydrous hydrogen fluoride to produce 3,3,3-triflurorpropene-1. The process comprises (A) mechanically mixing, in the absence of water, of (i) aluminum fluoride which has been prepared at temperatures less than about 400.degree. C. and (ii) a transition metal compound, the transition metal compound being selected from a group consisting of compounds of cobalt, chromium, iron, manganese, nickel, titanium, and vanadium; and (B) contacting the mechanical mixture with sufficient anhydrous HF to convert the transition metal compound to a transition metal fluoride. Also described is the catalyst. Additionally, a process for the preparation of 3,3,3-trifluoropropene-1 in which the catalyst is utilized is described.