Thermoplastic polyurethane elastomers (TPUs) containing aliphatic polycarbonate soft segments and hard segments formed by 1,1 '-methanediylbis(4-isocyanatocyclohexane) or 1,6-diisocyanatohexane and a combination of two chain extenders, i.e., 2,2 '-[sulfanediylbis(benzene-1,4-diyloxy)]diethanol and 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid (DMPA), were synthesized in a one-step catalyzed melt polyaddition process. The obtained colorless, transparent and high-molar-mass materials, which differ in the content of the soft segments (30 or 45mol%) and DMPA (10 or 20mol%), were subjected to a series of test. Their structure was examined by FTIR spectroscopy, and the thermal properties were studied using differential scanning calorimetry and thermogravimetry. Moreover, their Shore A/D hardness, tensile, adhesive and optical properties were determined.These modified by an ionic chain extender TPUs were characterized by generally enhanced transmittance (up to 92.7% at 800 nm), tensile strength (up to 49.3 MPa), hardness and adhesive strength, and decreased elongation at break with a slightly worsened thermal stability in comparison with the non-modified ones.