We use microwave (MW) absorption to induce rapid, uniform heating of the secondary high explosive octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) for decomposition analysis in a fast kinetic regime (10-2 s). Because HMX alone is MW inactive, composites comprised of an HMX-polymeric binder system doped with a small mass fraction (<1 wt%) multiwalled carbon nanotubes or graphite, were fabricated. The dielectric properties were measured (real and imaginary permittivity between 1 – 18 GHz), which is necessary for describing the expected MW-materials interaction and predicted heating response. The real component of the relative dielectric permittivity ranged from 3 – 4 while the imaginary component was 0.01 – 0.07, depending on the amount of carbon dopant added. Dynamic temperature measurements of a similar explosive composite under MW exposure were accomplished using fiber-optic temperature measurement techniques, and can be reproducibly correlated to the amount of MW energy absorbed in the sample.