PURPOSE: To produce a polymeric semipermeable membrane which exhibits high gas permeability and permselectivity by using an aromatic polyarylate compound derivatized from a dicarboxylic acid chloride and a cardo bisphenol having halo substituents on all ortho portions to hydroxy functional groups.

CONSTITUTION: A membrane is formed from a polyarylate compound having polymerization potentiality units as shown by formula I. (Ar is a 1-20C dihydrocarbon radical, R1 and R2 are each a halo substituent, (n) is an integer of >50 and L is a multicyclo crosslinked group, formula II or IIL). The semipermeable membrane produced in this way exhibits high gas permeability and permselectivity, therefore, it is useful in various gas separation applications. Particularly, this membrane is the most effective one for separation and recovery of oxygen and nitrogen from the air.