The complex shear moduli of the fluoroelastomer Viton A and four plastic bonded explosives LX-04, LX-07, LX-10 and LX-11, which use this polymer as a binder, have been investigated. LX-10, LX-07, LX-04 and LX-11 are composites of 94.5, 90, 85 and 80% 1, 3, 5, 7-tetranitroazacyclooctane (HMX) explosive, respectively, and Viton A. Viton is a random copolymer of 7 vinylidene fluoride and 2 perfluoro-propene monomers. In the temperature range from -150 to 120degreesC, two relaxations, the beta relaxation at -80degreesC and the glass transition at -22degreesC, were observed as peaks in the loss modulus in Viton A at 0.1 Hz. A third relaxation, T-alpha, was found above T-g in all four explosive formulations. The plastic bonded explosives (PBX's) showed antiplasticization phenomena. T-g of the explosives increased 2-3degreesC as the concentration of binder was reduced in 5% steps. Samples from the same original lot of LX-04 were evaluated after 20-23 years of service. The alpha relaxation occurred at 60degreesC as a peak in the loss modulus at 1 Hz. Both the beta and alpha relaxations were very broad and an accurate maximum for these relaxations was difficult to determine.