Thermoplastic polyurethane elastomers (TPUs) are generally synthesized by using the two-step, so-called prepolymer, method. To study the influence of the prepolymer on the properties of the final TPUs, four polyurethane prepolymers were prepared from a diisocyanate and a macroglycol by using different NCO/OH ratios. The prepolymers and the macroglycol used in their synthesis were characterized by using gel permeation chromatography, differential scanning calorimetry, and strain-stress measurements. Additionally, to test the adhesion properties of the prepolymers and the macroglycol, adhesive solutions were prepared, and the T-peel strength of plasticized poly(vinyl chloride)/prepolymer solution joints was determined. It was found that the properties of the prepolymers depend on those of the macroglycol used in their synthesis in such a way that the lower the relative amount of macroglycol units in the prepolymer molecules (higher NCO/OH ratio), the closer the properties of the prepolymer and macroglycol. The maximal theoretical degree of polymerization (<(DPn)over bar>(max)) determines the relationship between the macroglycol and prepolymer properties. Finally, the possibility of obtaining good adhesives from prepolymers, using low NCO/OH ratio in the synthesis, is evidenced. (C) 2000 John Wiley & Sons, Inc.