NOVELTY - Molecular sieve particles are dispersed in solvent to form slurry. A continuous polymer matrix is dissolved in slurry. Solvents, which do not dissolve polymer matrix in slurry are added, and stirred to form spinning solution. Hollow fiber mixed matrix membranes are spun from spinning solution. The solvents are evaporated to form a wet hollow fiber mixed matrix membrane. The wet membrane is dipped into water bath. The asymmetric hollow fiber mixed matrix membrane is washed and dried to produce asymmetric hollow fiber mixed matrix membranes.    USE - Formation of asymmetric hollow fiber mixed matrix membrane used for deep desulfurization of gasoline or diesel fuels, ethanol/water separation, pervaporation dehydration of aqueous and organic mixtures, and gas separations for separating carbon dioxide, methane, nitrogen, hydrogen, olefin, paraffin and light gas mixtures (claimed). Can also be used for separating organic molecules from water, and sulfur containing molecules from fluid catalytic cracking stream.    ADVANTAGE - The asymmetric hollow fiber membrane having improved selectivity and flux with respect to gas separation is formed.    DETAILED DESCRIPTION - Molecular sieve particles are dispersed in an organic solvent or a mixture of two or more organic solvents to form molecular sieve slurry. A polymer or a blend of two polymers as a continuous polymer matrix is dissolved in the molecular sieve slurry. One or more organic solvents, which do not dissolve polymer matrix in slurry are added, and stirred to form a stable molecular sieve/polymer spinning solution. Hollow fiber mixed matrix membranes are spun from spinning solution using a hollow fiber spinning machine. The solvents are evaporated for predetermined time by controlling the air gap to form a wet hollow fiber mixed matrix membrane with a thin dense selective mixed matrix layer having thickness more than or equal to particle size of the largest molecular sieve particles on surface. The wet membrane is dipped into a water bath to generate porous non-selective pure polymer or mixed matrix membrane support layer below the thin dense selective mixed matrix top layer by phase inversion. The asymmetric hollow fiber mixed matrix membrane is washed and dried to produce asymmetric hollow fiber mixed matrix membranes with 20% or more increase in selectivity compared to the asymmetric polymer membranes prepared from corresponding polymer matrices.