The chlorination of high-titania slag to give titanium tetra-chloride is of growing importance. The present work was done to study the effect of some factors on the chlorination process in presence of solid carbon as a reducing agent. The factors involve the temperature, flow rate, and particle size. A synthetic slag near in composition to the natural slag obtained from reduction smelting of titani-ferrous ores was chlorinated in a fluidized bed silica reactor. A pre-chlorination step was necessary to get rid of the non-volatile chlorides causing the sticking and agglomeration of fluidized slag particles.