The synthesis and characterization of new aromatic homo- and copolyesters based on L-arabinitol and xylitol are described. These polymers were obtained by polycondensation reaction of the 2,3,4-tri-O-methyl-L-arabinitol or 2,3,4-tri-O-methyl-xylitol, or their mixtures with ethylene glycol, with terephthaloyl chloride or isophthaloyl chloride in o-dichlorobenzene or in the melt phase from the corresponding methyl phthalates. All the polymers were characterized by GPC, IR, and NMR. Their M-W values ranged between 11,500 and 46,500, with polydispersities from 1.5 to 2.3. They were found to be soluble in chloroform, but insoluble in water. In contrast with the homopolymers completely made with EG, they showed a significant hygroscopicity. DSC and TGA studies showed that the melting temperature of polyethylene terephthalate is depressed by the presence of pentitol units, whereas the thermal stability is kept above 350 C. Only copolyesters containing 10% or less of pentitol units showed melting and produced X-ray diffraction patterns characteristic of crystalline material. D-Arabinitol-based homopolyesters appeared to be more crystalline than those derived from xylitol and also presented a higher thermal stability. (c) 2005 Wiley Periodicals, Inc.