PolyHIPE are cross-linked, highly interconnected porous polymers with unique multiscale, open-pore structures that are based on high internal phase emulsions (HIPE). This work is the first to describe crystallinity in polyHIPE. This novel crystallinity was achieved by using monomers with n-alkyl side chains (acrylates and methacrylates). Such crystallinity in polyHIPE could potentially be used to produce porous shape-memory polymers. The higher the molecular mobility and the higher the molecular order (homopolymer vs copolymer, non-cross-linked vs cross-linked, acrylate vs methacrylate, long side chains vs short side chains), the higher the melting point (T-m) and the higher the crystallinity. Only the polyHIPE based on an acrylate with a relatively long (C-18) side chain exhibited a significant proportion of its melting peak above room temperature and exhibited a significant heat of melting.