Water-blown flexible polyurethane foams were made by replacing 0 to 50% of VoranolŪ 4701 with epoxidized soybean oil (ESBO) in the B-side of foam formulation and PAPIŪ 27. The density, 50% compression force deflection (CFD), 50% constant deflection compression (CDC), tear and resilience of foams were determined. Molded plastic strips were also made by replacing 0-50% VoranolŪ 4701 with epoxidized soybean oil and PAPIŪ 27. Dynamic mechanical spectrometer (DMS) and differential scanning calorimeter (DSC) were used to determine the hard and soft segments and thermal properties of these plastic strips. The density of water-blown polyurethane foams decreased first when introducing ESBO into the foaming system and then increased. The 50% CFD trend was similar to that of density. The 50% CDC of foams increased and resilience decreased when introducing ESBO into the foaming system. The DMS results show that the peak of tan delta decreased with increasing epoxidized soybean oil content indicating that the hard segment increased with increasing epoxidized soybean oil content. The DSC results reveal that the Dcp decreased with increasing epoxidized soybean oil content indicating that the soft segment decreased with increasing epoxidized soybean oil content.