In this work, high molecular weight of heterocyclic aromatic polyimide consisting hexafluoroisopropylidene moiety in both diamine and dianhydride fragments was synthesised. The synthesis was performed via a two-step polycondensation route, which involved polyamic acid formation and chemical imidization. Subsequently, physical purification technique was conducted by microfiltration and re-crystallisation to obtain oligomers-free high molecular weight polymer. Selections of high purity and suitable solvent, type of amine catalyst, precipitation medium and reaction temperature were considered to favour the formation of high molecular weight polyimide. The synthesised polyimide was characterised by ATR-FTIR, which confirmed the presence of significant imide bands denoting the formation of imide linkage. Further confirmation of polyimide molecular structure was accomplished using 13C and 1H NMR. It was found that polyimide with high molecular weight (4500 KDa) was obtained with a polydispersity index of 1.48. Therefore, this polymer has favourable properties for gas separation membrane application. © Universiti Malaysia Pahang, Malaysia