Abstract: Triptycene-based micorporous polymer was functionalized with thioamide moieties via post-polymerization using phosphorus pentasulfide as a thionating agent in the presence of sodium sulfite. Gas adsorption experiments indicate that the modification leads to a reduction in the BET surface area of the polymer, from 1640 m² g^-1 for the parent TMP to 207 m² g^-1 on 74% conversion of nitrile to thioamide, while the resulting micorporous polymer possesses high H₂ uptake capacity, reaching 101.1 cm³/g^-1 (0.9 wt%) at 1.0 bar and 77 K, especially along with high selectivity towards H₂ over CO₂, N₂ and CH₄. The micorporous polymer presents a promising potential as efficient adsorbents in clean energy applications.