Novel polybutadiene-block-polystyrene-block-poly(ethylene oxide) (PB-b-PS-b-PEO) linear triblock terpolymers have been synthesized by sequential living anionic polymerization. Further catalytic hydrogenation led to polyethylene-block-polystyrene-block-poly(ethylene oxide) (PE-b-PS-b-PEO), a triblock terpolymer with two crystallizable blocks and a glassy middle block. Bulk morphologies have been studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) for different compositions. Thermal properties of the PEO block, as determined by differential scanning calorimetry (DSC), showed dependence with the block volume fraction (phi(PEO)) and its polymerization degree (N-PEO). The corresponding properties for the PE block are also functions of the polymerization degree (N-PE) and the volume fraction of the PEO block (phi(PEO)). Since the PEO block is the first to segregate from solution in toluene, its volume fraction determines the overall morphology and consequently the thermal properties of the studied terpolymers.