Abstract The detrimental effects of repeated thermal/field cycling across the martensitic transition on the transport, magnetic and thermal properties of Ni 45Co 5Mn 38Sb 12 are studied. With the help of resistivity and magnetization measurements, it is shown that the resistivity increases and the magnetization decreases monotonically with continuous temperature or field cycling across the martensitic transition. It is also found that the martensite to austenite transition temperature increases with repeated structural change. The changes occurring in these physical properties are seen to be irreversible in nature. The possible changes in the lattice and the microstructure by repeated structural change seem to be responsible for the observed variations.