Irregular networks based on the condensation reaction of hydroxyl-terminated poly(dimethylsiloxane) with cross-linkers were investigated. The networks have excellent damping properties in a wide temperature range utilizing the viscoelastic relaxation of the irregular network with dangling chains. NMR Cross-link Density Spectroscopy was used to explore the weight fraction of pendant chains and elastic chains in the elastomer. The transverse relaxation time for the elastomer was studied to explore the influence of pendant chains. The effects of the structure of cross-linkers and the molecular weight of precursors were studied in detail. Elastomers cross-linked by tetra-functional cross-linker (TEOS) have higher damping properties than the elastomers cross-linked by tri-functional cross-linkers (MTMS and OTMS). A damping elastomer based on irregular networks with effective damping (tan>0.3) temperature range of more than 250 degrees C (from lower than -60 degrees C to 190 degrees C) was prepared. POLYM. ENG. SCI., 56:97-102, 2016. (c) 2015 Society of Plastics Engineers