The present study addresses a systematic evaluation of the effect of crosslinking via terminal maleimide units on the gas transport properties through a dense polymer film of amorphous Poly(Arylene Ether Ketones) or PEK. The methodology for the preparation of crosslinked maleimide terminated PEK (or MIPEK) films from several blend ratios of different molecular weights of MIPEK is discussed in detail. The primary focus of this work has been to investigate the influence of different degrees of crosslinking on gas permeabilities and selectivities, with an objective of producing a highly selective membrane. It has been demonstrated that crosslinking markedly decreases the permeation of methane, without changing the values for molecules such as helium. / Master of Science