Intrinsically microporous soluble poly(imide)s were prepared via polycondensation from (±)-2,2′-diamino-1,1′-binaphthalene or 4,4′-(9-fluorenylidene)dianiline and four different linear comonomers: pyromellitic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxidiphthalic anhydride, and 4,4′- (hexafluoroisopropylidene)diphthalic anhydride. The porosity of the resulting eight poly(imide)s was determined by nitrogen, argon, hydrogen, and carbon dioxide sorption for precipitated and cast samples and compared. While only the stiffest and most porous poly(imide)s were able to adsorb nitrogen and argon, almost all polymers were able to adsorb hydrogen and carbon dioxide. On the basis of the sorption results, it was possible to determine the limit of intrinsic microporosity. The processing of the polymers has a major influence on the porosity as investigated by gas sorption and X-ray scattering. Solvent cast films are denser and can therefore be regarded as thermodynamically stable. Interestingly, we observed selective gas sorption phenomena (high carbon dioxide sorption but low hydrogen sorption) for some of the polymers. Finally, we investigated the response of one poly(imide) thin film to changing gas atmosphere by ellipsometry.