Poly(ethylene 2,5-furandicarboxylate-co-ethylene succinate) (PEFS) copolymers of 2,5-furandicarboxylic acid (FDCA) and succinic acid with 11.98-91.32 mol % FDCA composition were synthesized via melt polycondensation in the presence of ethylene glycol using tetrabutyl titanate as a catalyst. PEFSs' molecular weight, thermal properties, and molar composition were determined by Fourier transform infrared spectroscopy, gel permeation chromatography, intrinsic viscosity, H-1 NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (H-1 NMR analyses. DSC analysis revealed that PEFS copolymers' melting temperatures differed depending on EF units' percentage. TGA studies confirmed that all PEFS copolymers' thermal stability exceeded 300 degrees C. From WAXD analysis, it is observed that the PEFS copolymer crystal structure was similar to that of PES when EF unit was 11.98 mol % and to that of PEF when EF units were 74.35 and 91.32 mol %. These results benefit this novel biodegradable copolymer to be used as a potential biomaterial. (C) 2013Wiley Periodicals, Inc.