The research described in this thesis is directed towards the synthesis of novel monomers for preparing Polymers of Intrinsic Microporosity (PIMs). Each new monomer contains two catechol units fused via a spiro-centre, which adds a necessary site of contortion, and all are compatible with an efficient polymerisation reaction with 2,3,5,6-tetrafluoroterephthalonitrile. It was anticipated that the resulting PIMs would possess enhanced properties (e.g. microporosity, solubility gas permeability etc.) due to the polar and polarisable substituents that these novel monomers contribute to the polymer structure. This first part of this work describes the synthesis of two families of monomers. The first is based on the spiro-bisindane structural unit in which the spiro centre is shared by two fused five-membered rings, similar to the commercially available 4,4',5,5'-tetrahydroxy-3,3,3',3'-tetramethyl-l,r-spirobisindane, which was found to provide highly microporous polymers in previous work. Various groups (e.g. ketone, phenyl, fluorene) were introduced in place of the four methyl substituents. The second family of monomers is based upon l,l'-spiro-bis(1,2,4,5-tetrahydro-6,7-dihydroxynaphthalene) in which the spiro-centre fuses two six-membered rings. Similar substituents were introduced in order to make a direct comparison of properties to those of the polymers derived from the spirobisindane family. Additionally, the concept of adding "sacrificial" thioketal groups to the 4,4',5,5'-tetrahydroxy-3,3'-keto-1,1'-spirobisindane monomer was investigated, with the aim of temporarily increasing the solubility and processability of the poorly soluble ketone-containing PIM. The last part of the work is concerned with the results of the polymerisation reactions of these novel monomers with 2,3,5,6-tetrafluoroterephthalonitrile, followed by the characterization of the resulting polymers. In particular, the important physical properties of the polymers were assessed such as solubility, molecular mass (by Gel Permeation Chromatography - GPC), microporosity (using nitrogen adsorption), and thermal stability (by Thermo-Gravimetric Analysis - TGA).