The synthesis times required to produce high energy density compounds (C2B4H2)(n) and (C2B10H4)(n) by gas phase pyrolysis of the carboranes C2B4H6 and C2B10H12, respectively, have been measured at 1150-2000 K and carborane pressures of (0.3-3.0).10(-3) MPa. Kinetic model simulations of the synthesis have been performed. The temperatures, carborane pressures, and synthesis times required to produce small-scale (C2B4H2)(n) and (C2B10H4)(n) particles of 10 to 30 nm diameter are determined.