The first part of this series concerned the synthesis of novel polyisobutylene (PIB)/poly(dimethylsiloxane)( PDMS) bicomponent networks; the present paper concerns the structure and property characterization of a series of bicomponent networks of varying compositions (PIB wt %/PDMS wt % = 92/8, 70/30, 50/50, 35/65) having average molecular weights between crosslinks ((M) over bar(c)) of similar to 20,000 g/mol. According to network structure analysis by uniaxial equilibrium stress-strain measurements, the experimental (M) over bar(c)＇s are in excellent agreement with theoretical values. Hydrosilation end-linking efficiency was quantitated by the amount of sol and functional group analysis by H-1-NMR spectroscopy. NMR evidence indicates double-bond isomerization during hydrosilation. Network compositions by elemental analysis together with the low sol fractions indicate efficient crosslinking. These data suggest highly efficient network formation and well-defined bicomponent network structures. While PIE and PDMS showed T-g＇s at -72 and -124 degrees C, respectively, the bicomponent network did not exhibit clearly discernible phase transitions. The heat stability of bicomponent networks increased slightly with increasing PDMS content showing initial (10%) degradation temperatures at similar to 380 degrees C in nitrogen and similar to 320 degrees C in air. Tensile strengths and elongations were dependent on composition and varied in the 0.6-3.8 MPa and 600-1100% ranges, respectively. The swelling behavior was not much affected by composition.