Shape memory materials are capable tomemorize a temporary shape unless they are exposed to anexternal stimulus that triggers them to recover their permanent shape. The melting transition of crosslinked semi-crystalline networks can be employed to trigger shape recovery. Here, the secondary shapes are fixed by crystallization and the permanent shapes are established by chemical cross-linking. Compared with glassy materials, this class of materials is generally more compliant below the critical temperature, with a stiffness that is sensitive to the degree of crystallinity, and thus indirectly to the extent of cross-linking. Shape-recovery speeds are also faster for this first-order transition with an often sharper transition zone. One of the most widely used crosslinked shape memory polymers is polyethylene. Polyhedral oligomeric silsesquioxanes (POSSs) organic/inorganic hybrid materials are new generation nanofillers with the possibility of reinforcement and stabilization of the polymers. POSS with an empirical formula of (RSiO1.5)n (n is 8) has a Si–O– cage-like skeleton with organic sidegroups having reactive and/or nonreactive character. The chemistry of the side groups has a crucial importancebecause it controls the compatibility between POSS and polymers. Besides, the inorganic structure may provide polymers with molecular reinforcement, increased thermal stability, better flame resistance. In this study, the shape memory, rheological, thermal and mechanical properties of crosslinked polyethylene/POSS nanocomposites were investigated. The samples were prepared by melt compounding and subsequent crosslinking in hot-press. The effects of peroxide content, peroxide type and POSS content were examined.