Composite diaphragms were used in the investigation of electrowinning ti from ticl4 in a fused licl-kcl-ticl2 electrolyte. Composite diaphragms tested were of two general classes--those consisting of two or more solid materials and those which contained, in addition, a loose material. An electrowining cell using a flat diaphragm is described. The maximum current density for these diaphragms was 300 amp per ft2. Lower currents permitted longer operation times. The composite diaphragms gave electrode efficiencies that averaged approximately 60 percent, and the electrowon titanium was of good quality--some brinell hardnesses were as low as 68.