Ruthenium-catalyzed ring-opening metathesis polymerization (ROMP) of 6-R-B10H13 organodecaboranes containing strained-ring cyclic olefinic substituents has been found to be an important new method of generating poly(organodecaborane) polymers with higher molecular weights than previously attainable. The monomers, 6-(5-cyclooctenyl)-B10H13 (1), 6-(5-norbornenyl)-B10H13 (2), and 6-(4-cyclohexenyl)-B10H13 (3), were synthesized via the titanium-catalyzed decaborane hydroboration of 1 equiv of 1,5-cycloctadiene, 2,5-norbornadiene, and 1,4-cyclohexadiene, respectively. The syntheses of the saturated, linked-cage compounds 6,6‘-(1,5-cyclooctyl)-(B10H13)2 (4) and 6,6‘-(2,5-norbornyl)-(B10H13)2 (5) were also achieved by either the titanium-catalyzed decaborane hydroboration of the remaining double bond of 1 or 2 or the titanium-catalyzed reactions of 1,5-cycloctadiene and 2,5-norbornadiene with an excess amount of decaborane. ROMP of 1 and 2 using either of the Grubbs catalysts, Cl2Ru(CHPh)(PCy3)L, L = PCy3 (I) or...