A hollow fiber membrane is made by covering a tubular supporting structure with a membrane dope and converting the membrane dope into a solid porous membrane wall. Optionally, a textile reinforcing structure in the form of a circular knit may be added around the supporting structure before it is covered in dope. The reinforcing structure thereby becomes embedded in the membrane wall. The supporting structure may be soluble in a non-solvent of the membrane wall, for example water, and may be removed from the membrane. Alternatively, the supporting structure may be porous. A porous supporting structure may be made by a non-woven textile process, a sintering process within an extrusion machine, or by extruding a polymer mixed with a second component. The second component may be a soluble solid or liquid, a super-critical gas, or a second polymer that does not react with the first polymer.