The martensite structure in a Ti 36 Ni 44 Hf 15 Cu 5 ribbon annealed at different temperatures is investigated. When the annealing temperature is <873K, spherical (Ti,Hf) 2 Ni particles 20–40nm in diameter precipitate in the grain interior. Transmission electron microscopy analysis shows that (001) compound twins are dominant in the ribbon containing homogeneously distributed (Ti,Hf) 2 Ni precipitates. When the annealing temperature is 773K, the boundaries between the martensite domains with the (001) twins are blurry and vague. When the annealing temperature is 873K, four types of boundaries among the martensite domains are found: {111}, (001)//{111}, {113} and (110)//{113} types. When the annealing temperature is 973K, the (011) twins become dominant, and the martensite variants show mainly spear-like and mosaic-like morphologies. However, martensite domains with (001) twins also exist around the coarse (Ti,Hf) 2 Ni precipitates. Fine (Ti,Hf) 2 Ni precipitates should be responsible for the improvement in shape memory effect and the superelasticity of Ti–Ni–Hf–Cu ribbons.