Polyimides (PIs) based on 3,3',4,4'-oxydiphthalic anhydride (ODPA) and 4,4'-oxydianiline (ODA) end capped with two new monoamines and other four different monoamines have been synthesized with a view to study the effect of different functional groups at the end of polymer chain on solubility, gas permeability, and thermal properties. The new monoamines have been synthesized from 3-pentadecylphenol, obtained by hydrogenation of cardanol, a major constituent of cashew-nut shell liquid. Introduction of different functional groups at the end of polyimide (PI) based on ODPA and ODA, by end capping with different monoamines, alters oxygen and nitrogen gas permeability, solubility, and thermal properties.