A series of rubber composites with ultra high cis polybutadiene (UBR), NUC1-3, SBC1-4, SUS1-4, was prepared, and their vulcanized properties were measured and analyzed. The ultra high cis polybutadiene was prepared with the monomeric neodymium catalyst, Nd(neodecanoate)(3)(.)(neodecanoic acid). NUC composites were composed of natural rubber, ultra high cis polybutadiene, and carbon black. In the composite of a low carbon black content (NUC1, 45 phr), a high abrasion-resistance and a significantly low rolling resistance (tan delta(60 degrees C), 0.04) were obtained. According to the AIM study of NUC composites, abrasion resistance was closely related with surface morphology. In the SUS composites prepared with SSBR (solution styrene-butadiene copolymer), UBR, and silica, as the content of ultra high cis polybutadiene increased, Delta cure torque (M-H-M-L) increased with fast cure kinetics. SUS4 showed high elongation and tensile strength with excellent abrasion resistance. Rolling resistance was improved as the content of ultra high cis polybutadiene increased. The SBC composites were prepared with SBR (emulsion styrene-butadiene copolymer), ultra high cis polybutadiene (or high cis polybutadiene), and carbon black. It is remarked that abrasion resistance and Delta tan delta (tan delta (60 degrees C) - tan delta(0 degrees C)) are increased with ultra high cis polybutadiene. (c) 2007 Wiley Periodicals, Inc.