In this research project thirty three new polyimides (PI-1 – PI-33) were synthesized from two series of diamines by polymerization with commercially available dianhydrides, pyromellitic dianhydride (PMDA), 4,9,10-perylenetetracarboxylic acid dianhydride (PD) and 3,3’,4,4’-benzophenonetetracarboxylic acid dianhydride (BD). Two series of diamines having azomethine (Series-I) and azomethine with ether linkage (Series-II) with aliphatic substituent’s like –CH3, -OH, -OCH3, -Cl were synthesized. The polyimides were synthesized by a conventional two steps method which involves the ring opening polyaddition at room temperature followed by the imidization either by thermal or chemical methods. All the synthesized diamines and polyimides were characterized by using different techniques like elemental analysis, TGA, FT-IR and 1H-NMR. All the spectral data were found in good agreement with the proposed structures of polyimides. These synthesized polyimides were also subjected for the study of organosolubility, inherent viscosity, molecular weight measurement, moisture absorption, thermal behaviour, crystallinity and thermodynamic parameters. The organosolubility of the synthesized polyimides were checked in different solvents qualitatively. The majority of the polyimides were found soluble in common polar aprotic solvents like m-cresol, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N,Ndimethylacetamide , tetrahydrofuran (THF) and sulphuric acid at room temperature as well as some of them were soluble on heating. The improvement in the oraganosolubility of the polyimides might be due to the presence of aliphatic substituents and ether linkages in the backbone of the polyimides which reduced the chain-chain interactions and hence enhance the chances of penetrating solvent molecules into polyimide chain. The inherent viscosities were found in the range of 0.59 – 0.85 dLg-1 indicating the moderate to higher molecular weight of polyimides. Weight average molecular weight (Mw) and number average molecular weight (Mn) of the polyimides were found in the range of 59,000 – 86,000 gmol-1 and 36,000 - 53,000 gmol-1 respectively. Moisture absorption capacity of the polyimides was found in the range of 0.38 - 0.89%. The moisture absorption capacity of the polyimides is greatly influenced by the chemical structure of polyimides. The polyimides exhibited excellent thermal properties having glass transition temperature g in the range of 220 – 292°C and the 10% weight loss temperature were above 400°C without significant weight losses up to 360°C. The polyimides PI-23 – PI-33 having 3,4,9,10-perylenetetracarboxylic acid dianhydride (PD) showed better thermal stability due to the rigid structure of dianhydride. Most of the polyimides displayed amorphous pattern in X-ray diffraction analysis. The polyimides of 3,3’4,4’-benzophenonetetracarboxylic acid dianhydride (BD) and pyrromellitic dianhydride (PMDA) units with azomethine linkage having aliphatic moieties diamines displayed semi-crystalline pattern. The values of thermodynamic parameters , activation energy, enthalpy and entropy fall in the range of 31– 54 kJmol-1, 29 – 52 kJmol-1 and 0.15 to 0.26 kJmol-1K-1 respectively. Due to improved solubility and better thermal stability these polyimides could be applicable for high performance polymeric materials applications like high temperature application, as heat resistant polyimide materials, in the synthesis of plastic materials, in organic materials, in magnetic materials, etc.