Cellulosic polymers were tested by measuring their permeabilities of propane and propylene. High permeabilities and selectivities were obtained with ethyl cellulose membranes. Hollow fibers coated with ethyl cellulose were made through a solution coating method. Microporous polypropylene hollow fibers were used as base material. A dense layer of ethyl cellulose about 6–10 μm in thickness was formed on the microporous hollow fiber. The performance of a coated membrane column was tested for the separation of propane and propylene mixture gas. It was concluded that ethyl cellulose membranes have a good potential for the separation of olefins form saturated hydrocarbons.